Make a test strip. Set the enlarger height to cover an 8x10" sheet and mark that height on the column so you can use it in the future. Start, say, at f:8, and take one neg to make a test strip, say with 6 patches at 3 second intervals, develop, and see which spot on the strip is the minimum time to give you the maximum black in the unexposed parts of the film, and use that time for the whole sheet. If the whole test strip is off base, change the aperture or time interval and try again.
Now you might find that a proof sheet at minimum time for the maximum black doesn't give you good proof images--that's telling you that you need to adjust your exposure technique in the camera or film development time. Make a note of it, make another proof sheet so that you can see the images as best you can, and think about what you have to do to get good images on your next roll, if you expose your proof sheet for the minimum time for maximum black, because if you can do that, your negatives will be easier to print.