It is not possible for your score to improve as soon as you pay your credit card ... no. Your score won't improve until the creditor reports the new balance to the credit bureaus. They usually report this a few days after the monthly billing period ends. So if you pay your card down in the middle of the billing period, it might be 2-4 weeks before your score comes up. If you pay right at the end of period, it might be a matter of a few days to a week. Some creditors update weekly. It shouldn't take more than a month though, regardless of when you send your payment in.
If you're really wanting to know, call the credit card company and ask them when they report to the bureaus. Some do it on a specific day monthly, some do it twice a month .. some do it weekly. Sometimes 1st of month .. sometimes 30th . it just depends. Just remember, theres always a lag time from when you paid the credit card company, until the time they report it to the bureaus. Your score won't change, until the bureaus get the updated payment information from your credit card company.
sparky