It depends on a few things. I noticed the problem is worse with less microstepping (1/2 or 1/4 steps) as opposed to more (1/8 or 1/16). You usually have to run a print for a few hours before noticing anything.
At 1/8 steps nothing appeared until the last 20min of my 3 hour print.
At 1/8 steps nothing appeared until the last 20min of my 3 hour print.