In Zone 10, it probably doesn't matter unless there is a freeze......and that would only affect the mammey...not the persimmon or mulberry. Hydration is also an issue if you are in a dry winter location....but that can be managed. So I would go ahead with the purchase and planting of the persimmon and mulberry and decide if you want to gamble on planting a mammey. If planted, keep it well hydrated and protect in the event of a frost or freeze.
I agree with Harry. If you are planting a Mamey in the dry season, make sure you check it every single day! It is very water-hungry when just planted. If you see the leaves starting to close up, water it. Most likely you will be watering it every day or every other day until it gets established which should take a couple of months.
hmhausman
tropicalgrower89
adiel