Pre-flower or not ?

Yes, your plant is in the pre-flowering stage. You can tell by the small white hairs (pistils) just starting to poke out at the nodes (where branches meet the main stem). The top growth is tightening up too, which is a sign that it's preparing to stack buds soon. Those clawed top leaves are a bit stressed, but nothing too alarming — likely from the high PPFD or slightly warm temps, like we discussed.

keep an eye out for clusters of pistils. little white hairs and those are preflowers. im assuming its an auto flower if youre waiting for flowering to start. if its not an autoflower then make sure you decrease the light schedule to 12/12 to induce flowering. autos normally start flowering around week 4 but some start later and some earlier. keep an eye out for your plant starting to get bigger faster than normal. that would be the initial stretch that can sometimes come before preflowers or pistils and can be an early sign of your plant transitioning into