Of course, testosterone aromatizes even when receptors are not saturated; otherwise, no normal man would have even a microgram of estrogen, etc., in his body, which would be fatal. However, the key here is to find the right amount of exogenous testosterone so that aromatase doesn't exceed normal levels too much.
To be honest; I'm always very sceptical when somes asks questions concerning "managing estrogen while test-cycle". The reason is quiet simple: Not only too low testosteron f.e. after a cycle can cause problems, too low estrogen levels within the cycle can cause even worse problems.