WHETHER ONE HAS TO START SANDHYOPASANA ONLY WITH SAYAM SANDHYA AFTER BRAHMOPADESA?

(1) According to VyAsa, after obtaining gAyatrI, one should start from sAyam sandhyA.
gAyatrIM tu guror labhdvA sAyam sandhyAmupakramet !
(2) According to gautama, starting from sAyam sandhyA one shall do trikAla sandhyA.
sandhyA trayam tu kartavyam sAyamadi tatah param !
(3) According to pracetas, one shall do sandhyopAsana starting from sAyam sandhyA.
abhyopAsayet sandhyAm sAyamAdi yathAkramam.!
Kindly note that according to jaimini , one shall start with mAdhyAhnika sandhyA.
tato madhyAhna sandhyAdi sarvakarma samAcaret !
According to our traditional practice, we start with MadhyAhnika sandhyA after brahmopadeSa.