I just plant my beans a couple days ago and need to know when it will be safe to plant so they don't start flowering. They're under lights and not even up yet so it will be a while anyway. I get 14 hrs of sun on May 23, so I assume after that it's safe to put them out. Is this correct?
I think I understand your question. If you get only 14 hours of daylight on May 23, that would place you at or below the 34th latitude (around where Atlanta is, or just a stone's throw north of Phoenix). Unless a southerner like yourself lives in the mountains at higher elevations, I'm guessing frost is likely something very rare even in mid-winter there.
I'm in Canada, so our daylight exceeds 15 hours even in the southern part of the country by May 23. This gives us northerners an extra hour or more to play around with indoor day length before moving our plants outdoors. Even then, the CanadaGrows subreddit gets a couple rare posts each late spring concerning premature flowering by the day length reduction upon bringing them outdoors when a standard 18/6 light cycle was used indoors. This seems to be rare, and perhaps stress from transplanting, the strain, lack of hardening off, and environment were the culprit. TBH, I've never had flowering being triggered from the sudden 3 hour drop in daylight upon being planted outside.
But you have 1 hour less to work with. Will plants flower from 18/6 to a sudden 14/10? I know there are threads around the net where people have played with alternate light schedules and it seems that plants will definitely initiate flowering from 18/6 to 13/11. A gradual photo reduction may increase the tendency for plants to flower at higher daylight hours. For example, where I live if our plants in late summer didn't start flowering at 14 hours of daylight, we'd have to chop them down and use it all as mulch because there is no way they'll have time for flowers to develop before snow and freezing temperatures arrive.
I wouldn't worry about it too much, but if you want to play it absolutely safe and reduce stress you could use a 16/8 light schedule while your plants are inside if you want to plant out by May 23rd. As others have said here, don't forget to harden them off to the sun and weather gradually before moving them to their permanent spot.