You can already get a t-34 before a p4. Most players choose a t-70 beforehand which is an optional investment and for obvious reasons delays the t-34.
I'm really tired of this myth that the p4 comes out earlier than the t-34 as it'd only be true if the t-34 is locked behind t-70, which it's not.
I never said that the T-70 is mandatory, i only said you should get out a T34/76 before PZIV if you don't build a T70.
Look at the fuel costs. Ostheer reaches T3 building at 145 fuel if skipping all other buildings and light vehicles.
Soviet gets T4 building at 185 fuel if skipping grenades, light vehicles and second Tier building.
In reality Ostheer will build one building at least and Soviet will go most probably for grenades or for other Tier building. Either way the difference between Ostheer T3 and Soviet T4 is pretty much the difference in fuel between T34/76 and PZIV without building a T70. So there isn't much of a Time Window for T34/76..