When to pay depends on what your goal is: to use the bank's money for as long as possible, or to maximize your score. It sounds like you're interested in the later. That being said, if you're not planning on apping for something (something substantial) in the near future, many will advise you against driving yourself crazy with optimum CS maximizing payment schedules. But here goes...
You're fine charging something and paying it off ASAP, end of day, end of week, etc. The key is to have $0 reporting on all cards but one at statement cut. Most cards* out there have their statement cut about 3-4 days after the payment due date. The amount that shows on the statement is what gets reported to the credit agencies.
If you really want zero to report, you will also likely have to stop using that card from about the payment due date until after the statement generates to make sure that something in pending doesn't report. Some cards will let you pay before something fully posts, some won't. You can always push payments from your bank rather than pay at the CC site, but IME that's not as predictable as to when it posts, so if I care about a payment showing up ASAP, I pull the payment from the CC site.
*I said most cards because US Bank (and I think many CUs) are the exception. They cut their statement whenver, but they report whatever the balance is at the end of the month.
