How long is a reasonable time to wait for my final pay?

I started a new job recently and was let go after 3 weeks as the girl whose job I had filled didn't want to stay at her new job and returned to her previous job which meant my job was pretty much redundant seeing as I would be the spare wheel around the office.Since the office is a small one, with her return they decided not to keep me on, but of course couldn't fire me for that reason, so the manager gave some soppy excuse for letting me go, which was unnecessarily personal, but I'm just glad I'm out as the job sounded more exciting when it was offered but turned out to be so boring. On the plus side I have now decided to do what I have wanted to do for ages but just never had the courage to do: start my own business. I was fired on the 19th May and was expecting to be paid my final pay on the 25th which is when the company pays salaries but I haven't received anything yet. How long should I wait to query it? I need the money urgently to get going with my new business.