I always thought that it doesn't depend on your cycle length, but it depends on your luteal phase (if you have a shorter luteal phase, you would be due for af earlier than someone with a longer lp ... therefore, someone with a shorter lp may not get their bfp until later than someone with a longer lp because they are probably testing around af due date). The cycle length determines when we ovulate, but 10 days past ovulation simply means you are testing ten days after you ovulated (whether your cycle is 20, 30, or 40 days). Best wishes!
you can get a BFP 10 dpo. I did (I had planned to wait to test but couldn't wait any longer to find out). I wish you the best.
Yes, it totally depends on your cycle length! The website peeonastick.com explains it better than I ever could. Hope it helps answer your question. Good Luck!