Tell me about how you knew it was time to switch from 2 to 1 nap!

LO is 11.5 mo old, and is one 2 naps at home but started daycare (MWF) a few weeks ago and is on one nap there (it's how the pre-toddler schedule runs). At daycare there's enough going on that she presumably makes it until 12:30 to nap okay (up at 6:30am) but at home she's out like a light at 9am for her morning nap. Lately she's been having issues with her afternoon nap. I've been waking her up from her morning nap (which kills me, I hate waking a sleeping baby!) to protect her PM nap, which was working for a while, but I went from waking at 1.5 hrs, to 1.25hrs and now today 1 hr and she's trying to sleep in her crib but not tired. She gets up and cruises and then lays down again and chills and then up. Which I suppose is better than when she stood up and screamed in protest two days ago against her nap! Is it time to switch her? She's just so tired at 9am! Bedtime is 7pm and I'll probably try to get her to bed a little earlier to compensate, but it's hard with work schedules. And she's always up at 6-6:30am with rare exceptions, no matter what bedtime is!