Raising funds for your start-up takes time and thus you should always start early. The timing of raising funds will depend upon the stage your start-up is in . Typically for an early stage start-up funds could be raised once you have a minimum viable product (MVP) and some paying customers. A thumb rule for early stage start-ups is to start at least 6 months prior to the time you actually need the funds. Raising funds can be a painfully slow process !
when you have prior market research regarding your idea/solution,competitors,marketplace and user/customer behaviors.
Anytime is a good time to startup. Fail a startup in your mind before actually starting up