Let me breakdown your question into two parts. Your first question is "From above we can derive that there has to be "nothing" at first, for "something" to be able to come into picture."
Actually, no. Brahma Sutras I.4.14-15 says (Swami Vireswarananda translator, available here - https://www.wisdomlib.org/hinduism/book/brahma-sutras/d/doc62753.html)
- (Although) as regards (things created, like) ether and so on (the Vedânta texts differ), (yet there is no such conflict with respect to Brahman) as the First Cause, (on account of Its) being represented (in other texts) as taught (in one text).
[Sankara's commentary] The Sânkhyas contend that though the Pradhâna cannot be the First Cause according to the Sruti, yet Brahman also cannot be taken to be the First Cause taught by the Sruti. Why? Because there is conflict as regards the order of creation; for some texts say that it is Âkâsa that was first produced from Brahman, some say that it is Prâna, others that it is fire. This Sutra says that though there are conflicting views with respect to things created, that is, as regards the order of creation, yet since it is not the main object of the Sruti to teach about creation, it matters little. The main object in these descriptions is to teach that Brahman is the First Cause, and with respect to this there is no conflict; for every Vedânta text holds that Brahman is that.
15. On account of the connection (with passage referring to Brahman, nonexistence does not mean absolute nonexistence).
[Sankara's commentary] A further objection is raised that even as regards the First Cause there is a conflict, for some texts say that the Self created these worlds (Ait. Ar. 2. 4. 1. 2-3), others say that creation originated from non-existence (Taitt. 2. 7). Again existence is taught as the First Cause in some texts (Chh. 6. 2. 1-2). Spontaneous creation also is taught by some texts (Brih, 1. 4. 7). On account of these conflicting texts it cannot be said that all the Vedânta texts refer to Brahman uniformly as the First Cause. These objections are answered as follows: “This was: indeed non-existence in the beginning” (Taitt. 2. 7). Non-existence here does not mean absolute nonexistence but undifferentiated existence. Existence was at the beginning undifferentiated into name and form. In the texts of the Taittiriyâ Upanishad Brahman is definitely described as not being nonexistence. “He who knows Brahman as nonexisting becomes himself non-existing. He who knows Brahman as existing is known by sages as existing” (Taitt. 2 . 6). This Brahman is again described as having wished to be many and created this world. Again “How can that which is be created from non-existence?” (Chh. 6. 2. 2) clearly denies such a possibility. “Now this was then undifferentiated” (Brih. 1 . 4. 7), does not speak of spontaneous creation without a ruler, for it is connected with another passage where it is said, “He has entered here to the very tips of the finger-nails” (Brih. 1 . 4. 7), where ‘He’ refers to this ruler, and hence we have to take that the Lord, the ruler, developed what was undeveloped. Similarly Brahman, which is described in one place as existence, is referred to in another place as being the Self of all by the word ‘Âtman’. So all texts uniformly point to Brahman as the First Cause, and there is no conflict as regards this.
The second part of your question is "Also, the first ever 'thing' would have born, has to be a "thought", because it's the command even for any action to happen."
The Aitareya Upanisad I.i.1 says (Swami Nikhilananda translator):
In the beginning [all] this verily was Atman only, one and without a second. There was nothing else that winked. He bethought Himself: "Let Me now create the worlds."
and in Nikhilananda's summary of Sankara's commentary it says:
Bethought: The creation is a spontaneous action, without any compulsion or logical necessity. How could Atman, who is devoid of sense organs, think? It is because omniscience is the very nature of Atman, and therefore He needed no organ for the purpose of thinking. Compare: "Devoid of hands and feet, He quickly moves and grasps." The object of His thinking was the creation of the world whose nature would be determined by the past actions of the living beings of the previous cycle for their experience of pleasure or pain as determined by their good or evil deeds.
The philosophy of Atman is stated in the text in the form of an aphorism (sutra). Later on, by the demonstration that names and forms are mere illusory superimpositions (adhyaropa) and then by their refutation (apavada), will be shown the unreal nature of phenomena and the sole reality of Atman. The verses up to the first sentence of I.iii.13 deal with the topic of illusory superimposition; next follows the refutation.
When Brahman or Atman is referred to as 'thinking' it is a reference to Saguna Brahman and not Nirguna Brahman as there is no differentiation within Nirguna Brahman. Realize also that when terms like 'thinking' or 'thought' are used it is to put these ideas into terms and words that we can relate to and understand; in reality these things are beyond our comprehension. In reality, 'thought' is a part of the physical universe and a part of the brain. If you don't think so, if you think your thoughts are independent of your body-mind system, stop eating for a few weeks and see what happens to your thoughts. Ref
In summary, when there is nothing to start, nothing does not mean absolute non-existence. The first thought that arose was in Saguna Brahman. Note also that it refers to the start of a cycle, there was no first cycle. There were an infinite number of cycles before this one, and there will be an infinite number after this one.
Reference: Chhandogya Upanishad 6.6.2 and 6.7.2