All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah and that Muhammad is His slave and Messenger.
First of all, we congratulate you for the blessing which Allaah has bestowed on you, which is embracing Islam, and we ask Him to make you firm and steadfast on His Religion until the day that you meet Him. We advise you to thank Allaah for this blessing by seeking beneficial knowledge, performing good deeds, and befriending righteous and pious women who would help you in doing good.
In principle, each prayer should be performed at its prescribed time; Allaah says (what means): {Indeed, prayer has been decreed upon the believers a decree of specified times.} [Quran 4:103]
Every prayer has its beginning time and its ending time, so it is not permissible to perform it before its time nor delay it until its time has expired without a sound Islamic reason, such as combining the Thuhr and ‘Asr prayers, or the Maghrib and ‘Isha prayers for those who are exempted, such as travelers and sick people for instance.
The Fajr prayer is only prayed at its time, and it is not valid to pray it before its time. So you should endeavor to find a way to perform the Fajr prayer on time.
For guidelines for those who embraced Islam while concealing their faith out of fear of their families, please refer to fataawa 92031 and 103137.
Allaah knows best.