Fit time is as soon as possible when thinking about new clubs or a first set. It’s virtually impossible to develop a consistent golf swing without the right equipment. Poor posture develops from the wrong length, poor path and face position from the wrong lie, poor grip from the wrong grip size and all kinds of issues from the wrong shaft, not to mention the problems with the wrong club head and set make up.
Experience is not necessary. Even if a golfer can’t hit 2 shots in a row the same, a good fitter can put something in their hands that will fit. A good fitter needs to have some teaching skills too and can make suggestions to help the less than skilled player. As the player improves minor adjustments can be made.
You wouldn’t walk out of a clothing store with a suit that needs to be altered. Don’t buy a stock, off the rack, set of clubs.