I'd do the same.Honestly, don't give it too much thought. Just pick up the camera and start recording. If you feel you have enough at the end of Sat to make a video, make one!If not, continue recording on Sunday and make it a weekend vlog. If you do have enough on Sat, make another vlog for Sun.
Personally, I would just focus on getting footage over the weekend and edit on big vlog - but that is just how I would do it.