I’m probably not the right person to be answering this thread, but… we moved house recently and kept our cat in. She was very very experienced at avoiding cars and lorries whilst out and about at our old house. Apparently cats form a mental map in their brains when they move somewhere new, even when they are kept in - no idea how, but this source said it takes 6 weeks.
We let her out after 4 weeks because she was really miffed to be kept in, and she was so happy at having her freedom again, but on her second day of being allowed out she was hit by a car and killed instantly on the very narrow, very quiet road outside our house.
It’s just one of those things. Conjunction of wrong place, wrong time, someone going faster than they should 🤷🏼♀️ She might have been ok for years and years, and it was just bad luck.
So I guess what I’m saying is your cat might be fine whenever you let them out, or they might not, and you just need to weigh up all the factors and make the best decision you can.
Wishing a long and lovely life, safety and happiness for your kitties. 💖
PS. Agree with PPs who have recommended AirTags