When my Poodle stop growing?

That question is always tickle, when you adopt a new poodle, hoping to get a small toy. Afraid if the seller gave you a bigger one.
It is safe, when you adopt the puppy on his/her 7-8months old. She/he would already have the tallest point.
But of course, if you are looking for that age, it is very difficult because all puppies usualy go to their new home on 1,5-2 months age.

If possible, see the the dam & sire, it will help a lot. The puppy will not grow far from them.
If you can not do that, maybe this size list below can help you to decide:

1,5 month - 14cm
2 months - 15cm
4 months - 20cm
6 months - 24cm
8 months - 26 cm

The rule about standard FCI height is in this link FCI Poodle Size

And...please get your puppy from trusted kennel....I found many illegal practice, the certificate is made up. It is possible the puppy is not a pure breed or the parents not registered as a pure breed, but they borrow other certificate to get a registered litter. Don't ever buy your puppy from money oriented kennel like this. They just want your money. Love and health not their priority.
But if you are seeking for a dog who will love you, it is fine, no need poodle pure breed...all dogs are loveable. Just don't let them cheat on you.