Tracking Something New

This is sort of picky of me, but if I start tracking a new factor that I have a theory about, won’t the app treat all previous days as “none” since I wasn’t tracking it in the past? Specifically I’m trying to track my fatigue and I have been wondering if certain foods for breakfast have any impact. I wanted to start tracking that either as a yes/no binary in nutrition or as a factor also yes/no binary. If I begin tracking today, it will count any previous days as though I did NOT have a high protein breakfast, even if I did, because I wasn’t tracking at that time. Is the answer just to not interpret that data’s correlations until I’ve been tracking for a month or something? How would you do it?