Is this plant starting to flower?

tough to tell early on... a magnifying glass may show in the middle of those fledgling leaves is a bunch of white hair.. the hair you see on preflowers at growth nodes *can occur before flower.. variation as to when or if that happens before flower, but is possible and not uncommon. hair at terminal nodes is the sure sign it's in flower... vege growth (stem elongation / new leaves) will slow and stop over 2-4 weeks from that point. Does not look like an autoflower in diary... so if you flipped the lgihts, it's "flowering".... it takes time before our eyes can see anything, but the transition actually happens within 1-3 days of uninterupted darkness of 10+ hous per day. it just takes 7-10 days before you can see anything, but it's happening... while growth is fast, initial growth is slow and tiny... but it keeps doubling and doubling and then we can see it... the uninterrupted darkness causes it, guaranteed by biology... a hormone feedback system.

It surely is, it surely is! Congrats! And good luck the rest of the way... :-D

Yes I'm at this stage with green crack Fastbuds,,I'm getting slightly yellow looks like yours,,,,half veg nutes,,, ready for bloom

Yes