Thanks to your advices guys, the plants survived the heat wave !
I had to reduce the light time due the hot temperatures outside, now that it's done and the temperatures back to normal, the light schedule is back to 18h/6h. I misted them frequently and I can tell how well it works, the leaves are way less curled up, the plants are still growing fast. I now mist them a little bit when the light turns off.
I started LST on day 17 and re-adjusted it on day 20, I think I'm doing it well but I could be wrong, comment and tell what I can do better ! I only water them once a week, I wait for the soil to be very dry, like 1cm deep or even more.
I noticed some pistils on the biggest plants, I guess they're already pre-flowering
Couldn't take much photos of this week, I had a lot of work and the light is on when I'm back home, I made a short video with lights on, I also heard music stimulate plants, so I tried lol