Hello

Agree 001! If you have just moved to preflower and flipped 12/12 with more red than give it about 2 weeks total. A flash of white will show at the grow tips.

I agree with numbers,

if you see any white hair in that terminal bud, then yes. If it is an autoflower and you have preflowers at growth nodes, it's very likely in flower.

Usually you will recognize a stretching in the state of pre flower. White pairs of hairs appear at the nodes. Some days later you will clearly see the first flower.

If those are autos, you look like you might be on the verge of it. The pale centers to the top in #1,#2 can sometimes indicate their transition and #3 looks like it might be starting to actually push pistils. I wouldn't change up your nutrients or anything just yet though.

A good way to view the flowering period is a standard ~9 week flower where the first 3 weeks can be considered a stretching or pre-flowering period and the remaining weeks your 'flowering-proper'. In reality it is all flowering, with the exception of hormone transport and such that begins with the flip not being instant. Different mediums and environments certainly play into a particular plant's flowering timeline. If you've flipped, I wouldn't expect guaranteed signs of flowering for up to 3 weeks.

First two photos - maybe. Other two - doubt..

Nein noch nicht. Ich erkenne noch nicht mal die anzeichen der vorblüte. Das dauert noch etwas