I'd say up to 5% if you can do it. Take care of all your needs first, or else you'll end up having to sell and it may not be at the price you want. I'd get into a retirement plan too, if you can. Crypto is way more risky and bitcoin is at its all time high. You say we're heading for the moon, but we may already be there.
5% is good percentage that you can use to trade devide from your salary.
If you want more percentage i think maximum by 10% monthly. Like above me said, take care all of your needs first because if you put more to bitcoin, you will put your needs in the high risk.
Its a good start actually to get 5% to your salary as a starting point to make some trade in any form of exchange site platform. While doing this matter you should forsake your prime commodities in your daily needs as long as your not earning big yet in bitcoin. Just wait until the right times comes.