Upconverting 720p footage to 1080p

I'm responsible for editing a project that was shot on a Canon DSLR.

The footage came to me in H.264 and was shot in 720p/60fps.

The final output needs to be in 1080p/24fps, as I want to export the film for playback on HDTVs, as well as a downloadable 1080p format.

I've ran tests converting the 720p footage to 1080p (including the 60fps to 24fps) in MPEG Streamclip into an Apple ProRes format for editing, and it all worked well.

My only question comes while editing the project.

Do I convert all the footage to 1080p/24fps/ProRes FIRST, and edit in 1080p on the FCP timeline OR do I just convert the footage to Apple ProRes (and 60fps to 24fps) but continue with 720p, and leave the upscaling to the final output? Is there any quality difference, or would one workflow save me more time/effort in the long run?

I appreciate any help on this!

Thanks you so much!

-Andre