I personally like to go T4 if I use T1, because going T1, T3 leaves me with no hard counter for tanks.
Yeah T3 needs ATGs from T2 to be affective vs tanks cuz T34s can't even take on a P4 reliably.
I think a viable opening can be going T1 off the bat while calling in Cons, then building Penals and cons alternating. Keep the Penals fighting constantly and merging with cons to get their experience up fast, Penals also will have an advantage over grens early game.
I've been doing 3 cons then retreat engiee as soon as you have MP for T1 and then going 1 Penal and sniper. Gotta work on my unit preservation though. MVGame