aquamoon, if you do decide to test this theory, I'd be interested to hear the results.
So far for me I add my macros near beginning of the day for plants (2PM, lights go on at 11AM) and they benefit from that. But before that, I used to forget to do it a lot so a lot of times I added it almost before lights went off. The next morning when the lights came back on, I could see the difference. So, so far from what I've seen, the plants benefit either time. But if you can get a conclusive before and after pic of both, that'd be a nice reference.