I'd probably go for the full A time anyway.
The guidance time for age is here:
https://babywhispererforums.com/index.php?topic=84884.0You'll see the A time for 7 months is 3hr 15 and that some are getting more (some are substantially more because we work on what suits LO to get the best sleep not on a one-size-fits-all schedule). Also that at 8 months the guidance is 3-4 hrs.
Your LOs adjusted age is 7 months but I have usually seen that over the months the adjusted age often gets closer to real age in terms of sleep needs so we could be looking at something 7.5 - 8 months roughly as a guidance and this means A time can be anything from 3hr 15 - 4hrs as guidance.
I'm still basing my thoughts on her previously having a long second A time and getting a good nap out of it, we've already reduced that A time from 4hrs (which I think she was having) to 3hr 40...and it could well be that she needs longer rather than shorter, we don't really have anything to base this on yet.
So in the case of having a morning CN I think what I'd try is the full A time but then be prepared to get in there quickly to help resettle if there is a mid nap wake up. Use W2S to shush/pat (or firm hand) her back to sleep if you can and just help her to stay asleep for a good nap length. You might even decide to go back in at 20 - 30 min and just stay through the nap to help out as and when needed on the days when you don't get a decent first nap.
Sometimes waking early and crying can be caused by being UT - I know it's confusing as it can be either OT or UT but if you run the routine for a while hopefully there will be a pattern to indicate which way to go.