Im i a bit late to start tranning stems at week 7 or better late than never?

Just support the branches best not trying anything if your in flowering a broken branch at this stage could cause stunted growth to the buds on that branch, support the heavier buds maybe use bamboo sticks and tie branches to that with just enough force to move out the way to allow light through the canopy if you have any buds not getting light other than that I wouldn't try to train it now it's a little late if its flowering heavy already. Start training as early as possible in veg this way the canopy is even when it flowers resulting in an even canopy and even light coverage