I took some aspirin today around five how long should I wait to breastfeed my 3 week old baby?

Feed when due. If you only took it once, you may breast feed when it's due. Aspirin falls into the L3 category which means "moderately safe" during lactation. Ibuprofen and acetaminophen are category L1 "safest". When in need, try to stick to one of these 2.
Not sure. No good answer to that question that I was able to find. . Peak ASA levels from what I saw was 9 hrs. Maybe a pharmacist would have a better idea. You shouldn't take ASA and breast feed.