how often? heck take em out everyday if you want, but you gotta observe the snakes behavior if your stressing them out too much.... obviously put them back. I got a ball python that is always tense when she out of her cage, ball up, or runs to a hiding spot, so i just let her be and maybe take her out for 10 minutes at a time hoping she will calm down one day. she still eats good, just wants to sit in her hide all day.
male lesser on the other hand I could take out every day for hours at a time and he would most likely enjoy having something new to explore. observe your snake their all different.
since yours is still young, their going to be threatened/stressed by more things compared to an adult. so don't feel bad that he/shes acting that way, 10-15 minutes at a time, obviously give em a couple days after eating, they will most likely come around.