EWs usually happen at that age because of being OT so i would be worried that stretching them too long to bedtime would result in an EW, not by putting them down earlier. my Lo usually does 12 hours at night but at that age we even had a few nights where she slept 13.5 hours because of putting her down early, so really, try it if the timing is right.
for today though...if they woke up at 3:35 at 5 mo the max A time after a 45 min nap is really only 1.5 hours, i would go for another catnap at 5 pm for 30 min and then do bedtime at 7pm. after such a short nap even if you try to stretch them to 6 this is too long and will result in Ot which is more likely to result in an EW and the problem continues.