Even the next day is silly. If the election is Thursday, it seems reasonable to count on Friday and the weekend, and have the new MPs declared on Sunday, ready to travel to London on Monday and get sworn in.
In the US, the election is in November and the president doesn't get sworn in until January. It could take a couple of weeks to count the votes and it would be fine.
In Blighty, we have paper voting. The polls close at 10pm, the manual count takes place overnight, and the result is typically known the next day.
How much more rapid do you need?