Advice on how to record when your face turns red after eating

I often experience facial redness after eating, so I plan to see a doctor for a consultation soon. Before my visit, I intend to take notes on the timeline between meals and the redness, but I am writing this post to ask what the best way to record this would be most helpful for the consultation!

First of all, when recording the time, should I write it down from when I started eating until when I noticed the redness, or should I calculate it based on when I finished the meal? Just in case, I am wondering if it would be better to write down both the start and end times and explain them during the consultation.

Also, I would like to know if it is okay to record approximate times, such as "between 30 minutes and 1 hour after eating," instead of precise minutes, when meal times are inconsistent or I notice the redness late. I also intend to write down the food names and approximate quantities; however, in cases like eating out where it is difficult to know all the ingredients, would it be acceptable to simply write something like "Eating out at OO Restaurant (Ingredients unknown)"?

Rather than making assumptions about the cause on my own, I would like to consult with the doctor based on the actual notes I have written. I would appreciate it if you could share any additional materials or tips that would be helpful to bring before my visit, besides this food diary!