Okay, Tech 1 reinforcements should be available 1 minute into the game, tech 2 at 5 minutes and tech 3 at 9 minutes.
There should be no other delay for reinforcements.
Why? The delay in reinforcements is dumb/meaningless because a) Reinforcements are already balanced based on credits cost, b) Auto recall limits the damages that reinforcements can do and c) baiting reinforcements strongly counters massively huge reinforcement waves
Basically, there's no point in having more reinforcements take longer to show up than less reinforcements: The cost of having more is the price. The time based on tech only balances the techs vs each other. More of the same tech vs less of the same tech makes no difference.
And if your enemy chooses to bring in a massive horde of 100 T1 tanks you can always simply retreat and re-attack, utterly wasting your opponent's money.