How to resume app restore after stopping it on first opening Google Play?
Use bmgr from adb shell. See this answer for a complete explanation of backup sets.

Root access is not required.

shell@maguro:/ $ bmgr list sets
  1234567890abcdef : droid48
  34567890abcdef12 : galaxy49
  ...

shell@maguro:/ $ bmgr restore 1234567890abcdef
Scheduling restore: droid48
done


This triggered a full restore of all the previously installed apps on my device instantly.