My friend is revising all the A2+AS topics hopefully before December so she can start paper papers and other techniques to test her knowledge.
I guess you can revise the AS alongside with the A2 like my friend as it builds up and helps improve knowledge on both. Or you can revise A2 Mon-Friday and AS in the weekends(you can stop revising for A2 content when you feel confident with the content). Hopefully, when you are confident with the contents, just do past papers after or potentially do past papers after every single topic.
Good luck! Hope everything goes well!