I'm no expert, and just as new at this as you are... I'm assuming this is also your first (is my first), but she was almost ready on her own to extend her A time. I really didn't have to do much. I have been finding that if I don't make that first A time exciting or playful (without being over stimulating) she can stay awake longer. If I just keep it low key and pretty calm she doesn't last long, so she will go to sleep sooner.
She usually starts to show tired signs at 8:20 ish. During the day the only WD she gets is the swaddle and the paci. Depending where we are, she might get more of a snuggle (Grandmas seem to sunggle for a long time - I'm okay with that, she goes down well without it too) And then she puts herself to sleep, and takes about 10 min to do that. Sometimes I need to replug the paci, but other than that, she's out.
One thing that I've learned with A time, is that it can be before E time and after. Sometimes our routine is: EASA, EASA, and that's okay, just as long as A is always before S.
The other thing is to remember to do things slowly. Change is big for these LO's, doing changes in 5 or 10 min at a time is plenty. If she is giving tired signs, I would be starting to put her down, otherwise she will get OT, and that is no fun for anyone. I know somedays it's hard because you don't really even get a sign, just all of a sudden - tired. No warning, no rubbing, no yawning - just whiny. Sometimes I think she is just learning so much about herself, and experimenting with how she wants to tell me things. But having a routine is the lifesaver, we both know what is next, and I can take my cue from that.
The last thing I've learned (at the top of this thread) is to watch to make sure she is not getting to much sleep during the day as it will rob her nighttime sleep.... no good. That would be the only thing I would watch for in trying to extend her S time in hopes to extend her A time, but hey, that might work for her. Not everything is the same for every baby.
I love that mommies from around the world can sit down just as they would with their girlfriends and hash these things out!!! Hope some of that post makes sense.