Yes. I do believe you can get the ceremonies done.
While not having the ceremonies will not prevent you from being a good Hindu, formalising these ceremonies is a good thing.
If you are ready to do this, you can get a mundan and Janeo done together on this Friday between 3:21pm and 7:43pm.
You should speak to the acharya and pandit at a mandir, while family is important usually at the ceremonies, seeing as your family did not previously participate, you may want your friends present. Any family which joins is welcome. The ceremonies should usually be done at your home, but if not the mandir may also be acceptable.
Ask friends to be present, because you will be busy with the ceremony and will not be able to do anything. Friends would be able to help you out with the food etc.
Additionally the pandit will give you the list of requirements for the Havan, but if you are not able to light a fire, the alternative is a coconut and a Kalash of water, dry rice, sandalwood paste, red thread, Kum Kum and some fruits and sweets. And You will also need a low stool for you to sit on.
You will need to invite a barber, and provide him a new pair of scissors and a shaving blade and straight razor, and two white towels.
For yourself you will need two sets of white kurta pyjamas, and two white towels, and a white duppata
On the day of the ceremony, you must oil your hair, wash it and bathe. Wear one of the kurta pyjama, and prepare your mind and body. Fast.
When the acharya arrives, do a full length pranam and touch his feet. Touch the feet of all your elders and friends present, they are here to give you blessings, you should feel no shame in touching all their Feet. Make sure you get the blessings of the barber too.
While this can happen before the Pooja time, Make sure that you sit down to Pooja at 3:21. The ceremonies will take some time.
The acharya will then tie your hair in 5 knots using grass or straw. You will have a Tilak done by the acharya and then by the attending people. Everyone will sprinkle rice on your head. Try and collect all that falls in the lap of your kurta or in one of the towels.
Have your friends hold the dupatta stretched over your head.
The acharya will then cut all of the five tufts of hair, and then hand over to the barber. The barber will wet your hair, please use dettol and warm water here, and then shave your hair except for a tuft of hair right at the crown. This is the Shikha. Make sure that all of the hair that is cut is collected. Have it fall in your lap. This hair is sacred and will need to be kept for a year.
Now that your head is shaved, you will need to have another bath. Have someone ceremonially pour water on your head and bathe you. You must now change into the new kurta pyjama. The previous one is to be given away.
You will now sit down to Pooja again and the acharya will lead all assembled in doing another Tilak to you. He will complete the prayers for the mundan.
For the Janeo ceremony, traditionally another headshave is done, however in this case the acharya may choose to do your Janeo also. He will take a long white thread and wrap it around in a loop. He will then whisper a mantra in your ear and loop the Janeo around one shoulder.
You should never remove the Janeo until the same time next year when you change it. You should have another headshave then.