I began the weaning process at 4 months using the gradual method, beginning by letting the foal eat alone in aisle, mom in the stall, after a week, separating for longer periods, then total separation. BUT, mare and foal next to each other in separate areas, they can see each other, touch noses, etc. My place is too small to totally place them out of sight and/or hearing, and my thoughts on weaning are to dry up the mare with less stress on the foal. I did that for 20 years and it worked well for me with heathly foals.
Never used the almanac, sun, moon, whatever, to me does not matter compared to the maturity of the foal, whether the mare is being pulled down, and the foal is fat and healthy. I think you could find an almanac in a book store.