IMO you are too late for a mid July harvest. Few strains are ready by 6 or 7 weeks--most strains take 8 weeks of flowering to mature to harvest.
LST is generally done during vegging and usually done if space and vertical height is a consideration.
I think that it is important to keep stress (even the low stress kind) to a minimum once the plants are put into flowering. However, it would be nice to see a side by side comparison grow to compare yields (we need pictures). So, should you decide to LST one plant, please start a grow journal and keep us all informed about your grow.
You are most likely not going to make your mid July harvest date, however, unless you harvest prematurely.:stuff-1125699181_i_