At the moment that you have played up gambling or making up some bets or risking an amount into something to earn something, then you can be already called a gambler generally. There are just that categorization on the level of gambler you are on which there are those who do play occasionally, weekly or on everyday. You can be classified as a gambler and there's no such kind of requirement for you to become one.
I dont know if its really that needed to talk up that much since this do comes with common sense. If you dont want to be called a gambler then you shouldnt be playing at all. There's no way that we can be able to tell on how long on a particular person been doing or playing gambling or on how much that they had spend already. There's no such thing that you can be able to have those metrics about into those manners.