Hi lindaloulou. At 16months I would say she is ready to transition to 1 nap. The fact that she is dropping the pm nap adds to this. I would say she is OT due to the long afternoons when she is not taking the afternoon nap. Its a tricky one because in an ideal world you don't want her to be OT when you start to make the transition, however this is seldom the case for this transition.
There are 2 ways you can do the transition, personally I favour the 1st one, but for some the 2nd one works better.
First way would be to start extending her morning A time 10-15Min's every 3 days or so until you get her doing closer to 5hrs A time in the am and let her sleep as long as she wants for this nap. The idea here being that if they are waking at 7am this puts the 1 nap at lunch time, which is where you want it. You then offer a catnap in whatever way you can in the late pm, just a short one to get her through till bedtime. Generally a 15min catnap will do her for another 1-1.5hrs A time, 20Min's nap 2-2.5hrs, 30Min's nap 3-3.5hrs. As she is waking early you should be able to squeeze in a catnap. If you cant get a catnap in then its early to bed. So if she only sleeps 1hr 20Min's put her down a good 40Min's early to allow her to tag lost day sleep onto night. As a rule I would say to offer her the chance to sleep at least 11-11.5hrs at night, so if she is waking at 5am then for now bedtime will need to be no later than 5.30pm. This early day can be shifted once you get her routine sorted and with any lick once she is less OT the early wakings should improve some on there own.
The 2nd way is to only offer a short catnap in the am of say 30Min's to start, then next nap hopefully a long one roughly 3-3.5hrs later, then when necessary you cut the am nap further to 20Min's and put down for long pm nap 2-2.5hrs later. The idea here is that you use the early catnap to get a good 5-5.5hrs between wake up and the long pm nap, gradually reducing the catnap until they can go the 5hrs straight from wake up.
I think as she is doing 4hrs already in the am I would try the first method as she is very nearly there already.
Leslie - Sorry this may contradict what I have said in the past, or what someone else has advised but I'm going to say it anyway
Are you cutting that first nap short or is she waking from it herself. If your cutting it short I would stop doing so and just let her sleep as long as she wants in the am, then offer a late catnap or early bed, whichever works best. It sounds like she is OT with those short naps so you may have to work to extend that first nap. I found W2S most helpful for this when transitioning.
Jmoran - If they are waking at 5/5.30am then 10/10.30am is as late as there nap should be. 6.5hrs A time is too long at there age. I would stick with the early bedtime, don't worry you wont be putting them to bed this early for ever, just until they have successfully transitioned. I also wouldn't be worried about them waking from their nap and needing resettling, just do what needs doing for the time being. I think it may be because they where a little OT before nap, they same way they might wake 45Min's after bedtime if a little OT at bedtime. I think the fact that they slept well on the earlier bedtime is a great start. It may not feel like it but your making good progress in the right direction
