Hello everyone, could you please tell me when your children transition…

Hello everyone, could you please tell me when your children transitioned to one daytime nap? My daughter can't fall asleep, she tried to put her down at 3 pm and it was sunny outside, and nothing helps at home either. The child doesn't go potty. Usually we have three naps, but something went wrong today. She cries and won't sleep. I stop putting her down immediately and play with her and she is happy...