if u have be the pro u must add this question only pro. I think so all who get money for life is pro. More regs and grinders consider themselves pro players, but in fact it is not so, just looking at them creates a picture that there win a lot of money, in fact, even the best poker players often spend giveaway when they win not even a large amount, and the contracts that they have with poker rooms are made for the benefit of poker rooms. Personally I hobby-player, but sometimes even me poker gives lots gifts.
You can be pro any time. (With your own money)
I think it you get good enough that others notice you and have good results
Getting stake as a horse is really the sign of a good professional as it mean someone is willing to put up some money on you