Hi EM,
I would really try not to extend his days longer than 7:00 pm. try it, you have nothing to loose, what do you think?
If your A times are giving you good naps than i ll stick to them, but my advice also is to let him sleep as much as he wants on these naps. I know I have adviced otherwise before BUT once I have actually tried it, I have found that cutting los naps was the worst thing I did for her, and as soon as I did it, we started having NWs!

!!!
so I stopped it and let her sleep as long as she wanted. The NWs are gone again for us and the EWs are 50/50 resolved.
when she is having 2 good long naps and a decent BT between 630 and 7pm we are then getting a normal wake up time, between 6 and 630. but when ONE nap is busted,eaning short, we are back to the EWs between 5 and 530!
AND, the trick is, the day she wakes up at 5:30 , I NEVER let her sleep before 9am. This also helped us alot in keeping our days stretched out. when your lo wakes before 6am I would urge you to keep him in his cot with zero stimulation unless he cries out. This is the only way he ll be able to last till 9am for his 1st nap.
i m not sure what everyday brings us... but some days are better than others and for now I m going along with this...
you are very close... big hugs
HTH