B Strep test, best time to do it?

Your midwives do not acknowledge GBS?! That is very odd since it can cause complications for your newborn. I too am seeing midwives and not doctors (Birth Center) and they are testing me at my next visit (37 wks). You should be tested between 35 & 37. Since you had it with your prior pregnancy, they may just treat you for it regardless. You need to bring it up to them at your next visit. Good luck!