5 years from new grad to L6 is way more realistic and normal than 4 years from new grad to staff, which is L7 at Amazon. If you're good a year to L5 is pretty normal and if you're exceptional 2 years from L5 to L6 is normal as well. The quickest L6 to L7 promo I've seen is 3 years, though that one started at L5 and has 7+ years tenure, so probably between 8-10 YOE total