After eating what would be an acceptable rise before coming back down. I often go up by about 5 or 6. So tonight I started at 6.9 and two hours after was at 8.1 but it got to 12.8 before coming back down.
The usual advice is to keep the rise to less than 2 after 2hrs. The maximum in between those times will depend on what you eat, and is also difficult to measure unless you have a CGM, but I believe even non diabetics may go up to 10 occasionally (not a rise of 10).
Food varies day to day due to losing most of my pancreas as I struggle to process a lot of foods. Because my pancreas does work at some points of the day it's hard to control. I have lantus which has brought the night time levels down but the daytime are all over the place and my levels rise by 2 to 3 just doing something and that's without eating. I put that down to being in constant pain when I move. I am using a CGM at the moment to try a get a better picture of what is happening.
For me, it depends on what I've had to eat. Even a fried egg can cause a small blip (< 1) whereas a slice of bread can cause a larger jump of 5 or so. Except for my treat on Sunday when I will have a slice of toast I don't eat anything that is obviously carby like potatoes, rice, pasta, cake, biscuits and chocolate.