As long as your NEO token are in the blockchain, you earn GAS.
You can claim it whenever you want.
...you got them backwards.
NEO is a coin
GAS is a token
For your info...
"Coins really only have one utility — to act as simple stores of value with limited-to-no other functionality. By “simple” value, I mean value not represented or manifested through a variety of dynamic functions. Tokens are a completely different breed all together. They can store complex, multi-faceted levels of value. Forget everything you know about bitcoin and pre-mined coins and that entire ilk of tech, Ethereum tokens are generated by a Smart Contract System (SCS), are highly programmable and have multi-functionality because of it. They transcend being just a coin, and through their array of functions become something much more — “tokens”. Technically, they are not “offered”, they are “generated”. Probably the most accurate phrase of what’s going on during an Ethereum token launch is to describe it as a “Token Generation Event”, but I’m not sure TGE has the same flare as ICO. Nevertheless, a coin does one thing, and a token can do many things."