Does GOD know us before our mind and body is developed ?
Yes GOD know us before our min or body is existed. Mind and heart will lead us to wrong direction, but only by following the soul one reaches GOD.
From Mahimna Strotra
अतीतः पन्थानं तव च महिमा वाङ्मानसयोरतद्व्यावृत्त्या यं चकितमभिधत्ते श्रुतिरपि। स कस्य स्तोतव्यः कतिविधगुणः कस्य विषयः पदे त्वर्वाचीने पतति न मनः कस्य न वचः॥२॥
Your greatness is beyond the reach of mind and speech. Who can properly praise that which even the Vedas describe with trepidation, by means of' 'neti-neti / not this, not this'? How many qualities does He possess? By whom can He be perceived? Yet whose mind and speech do not turn to the form later taken by Him (saguna) (2)