How to stop my cat from meowing?

I have a young cat, and he and his mum are only allowed outside at night when it is properly dark (safety because people can't see them). My young cat gets extremely excited about the thought of going outside, even when it is still light and he knows he has to wait a bit.

He just goes around the house meowing at the top of his lungs and comes for cuddles and nudges and tries to get you to follow him to the door and let him out. But we can't let him out when it is still day because it is too dangerous, once it is night, the door is opened and they can both run out and go on their outside daily adventure. They don't go far, but it's too dangerous for them if they go to the neighbours or on the reserve. At night if they do wonder over there, at least they can't be seen because it is dark and there aren't any lights. I'm not worried about the road, because they are both petrified of the front yard and cars.

I don't mind him meowing wanting to go out, as it's normally only 30 minutes until it's safe enough, but if there is any way to make him quieten down a bit...

I love him dearly so I am not letting him out in the day.

(the other cat is really quiet and calm so she's ok meowing wise)

I also do use a leash if he persists in the middle of the day, except recently I've been very busy getting work done so he has to wait until night.