Lockdown was when I thought day 25 was, but then again, I opened it up after that to candle them and saw movement so then I did Lockdown again...but they don't take 30 days. If I truly knew when Mama Mandarin started sitting on them 24/7, it was probably right about day 28. I've heard you jack up the humidity and start lockdown as soon as they internally pip...that is what I do with my Goose eggs with excellent results. So if and when I take Mandarin eggs again from their mama, I'll watch them and candle every evening til I see the air sac drop and them internally pipping, then I'll put them in lockdown. HOpe that helps...day 25 is nothing to worry about...candle them and wait for that air sac to get really low on one side and see if you can see them shadowing or pushing on it or already pipped thru the sac...then put them in lockdown with humidity way up (65-70%) . I'd LOVE to get some white Mandarins. Where are you- Florida? Darn.... I'd trade reg ones who are almost 2 weeks old too....
Good Luck!
Lisa