What month can I expect eggs?
It won't be possible to give an exact answer. All birds are different.
I can give an example with my pullets. But it's an example, not a guarantee.
My flock is 6 months (23.5 weeks)
Most of my pullets had their first eggs at 18-22 weeks (and I didn't see who or when for most of them)
Both you and I have at least one Marans, Orpington, Wyandotte, and Brahma. So I'll discuss those.
Light Brahma - 23 weeks (I think that's early)
Silver Laced Wyandotte - not laying yet? (I could be wrong, but I've never noticed her in a nest box.)
Lavender Orpington - 18-22 weeks
Marans... I have 3
Golden Cuckoo Marans - 18-22
Splash Marans #2 - 18-22
Splash Marans #1 ‐ 17.5 weeks (I think that's early, but she is smaller than the other Marans)
If you assume your chicks were hatched, say, April 1st? I'd say the first might lay in August at the earliest.
But with that being the colder season, some birds just hault egg production even if they've never had an egg.
*edit to add
It isn't impossible that they'll lay early, or lay through the winter even. This is more of a "well, you might be disappointed, but sometimes..."
As long as your nests are ready before, and you have calcium for them. I almost didn't have my nests done in time.