Hans i do the same thing, i always switch to bloom nutes around 10 days after showing sex, so say they sex on day 15 i will introduce bloom nutes on day 25, a little nugget i found right at the beginning of my adventures in one of SB's grows. You see there is still enough N being fed to the plants to allow for the stretch to continue without any problems, the plants i grow average around 80-100cm, not bad for autos. You see i think the opposite from the convention, i think by delaying the introduction if bloom nutes, you may be in fact slowing down the bloom process, therefore increasing the finishing time. Using the early switch method, i have found i can bring all my plants in on the advertised time, if not earlier. Now here comes the disclaimer... I have only done this with DP genetics Just thought i'd throw it out there brother.