......after an evening, and a long afternoon that seemed it wouldn't end in my 95+ garage... I have countersunk all those holes on the wing spar flanges.
I too started my wing kit in the heat of summer last year. Whew, I feel for you. Just wait until you get to do all the riveting inside the wing skins. Great weight loss!
Those countersinks are certainly one of the "puckering" parts of the build. I think I checked and re-checked about a dozen times to make sure I got each hole with the right countersink. Good bit of the job to get done. Now you can look forward to all the fibreglass work