To me npp should check (and offer) updates when exiting, not when starting. Update popup can be quite annoying showing up when you need a quick look at some file.
currently I don’t see a way to reconfigure this and in addition
I would think it might be more useful to check on start but running in the background.
When exiting npp user should be asked about a new version ready to install with an option to skip
this release at all or to postpone installation for another few days.