Start of bloom = end of LST?

Pre-flowers is not flowering, it is just an indication that flowering proper is about to commence, usually in roughly 2 weeks time. She will still grow some more and I would stop with the LST and let her do her own thing from now onwards...the less stress the better. Keep feeding with "grow" nutrients and don't change to "bloom" nutrients until there are small budlets starting to form, probably in another 3 weeks. Your plant still needs adequate nitrogen right now to help with any stretching and to transition to the flowering phase. Whatever you do, do not cut any more leaves off, she will NEED them to make the energy she needs to grow her flowers. You can still do LST up until the second week of proper flowering without harming the plant, so for another 3-4 weeks from this point, if you really want/need to.