When do you resolve a 1 action cast time spell?

So I think I’ve read somewhere that spells that cost 1 action to cast are resolved in the beginning of your next turn and you make any sort of attack roll then. But I’m not so sure of it and I couldn’t find a definitive answer in the player’s handbook.

When does the spell resolve if its casting time is 1 action? And when do you make the roll for any effect it makes? I would like your source on this so I can reference in the future as well. Thank you 😀