They're nocturnal, so if your snake is "nippy" (There's no real way to tell if it's going to bite when you pick it up without just trying sometime), early evening hours, after the lights have been off a little, is a good time. Once it's a little older you can start handling it at different times, but it's good to let it get comfortable with its new life and everything first.
I wouldn't worry about picking it up when it's balled up. Mine's always balled up; I rarely catch her stretched out on the move. I use a hook to pick her out of the cage our of habit with everything else I've owned. Initially being picked up can be startling, but once it's out, most snakes are pretty friendly.
I wouldn't hold the snake more than once a day, maybe twice every once in a while. Too much handling can stress snakes. Also, if you're going to have it out for an extended period of time, think about where you're going to take it. In your hands the snake can't move if it's too hot or cold, or if it doesn't like the lighting. Semi-dim lighting, maybe towards twilight when it's still pretty warm outside, is a prefect time. Here in Tucson, after the daily monsoon, it's about 75% humidity outside and 87 degrees; I put my bp on the staircase rails and we sit there for maybe 20 minutes.
Also, the usual... if you're going to hold it once or twice a day, do it a favor and give it a break for a couple days after eating, and stay away from it during its shed cycle. It's not always necessary, you *could* hold the snake a day after eating and towards the beginning of its shed cycle... but why risk it. Besides, it'll be getting a lot of handling otherwise, and a break weekly and a longer break every month and a half or so will be a good cycle.
IF your snake turns out to be a little aggressive, it should pass. In the meantime, stay away from its head, don't "pet" it, etc., and it'll get used to being held.