IK/FK advice before I start animating

I’m getting ready to start my first Blender character animation and I’d like a bit of advice.

I have 2 characters skinned to armatures with IK on the legs and arm, actually they’re mostly based on Harkyman’s rig.

I was wondering wether or not I should key my IK constraints off when I have to do some FK. Say I want to get my character to rest his elbows on a table and hold his chin in his hands, can’t really do that with the IK. I can get them pretty close, and then rotate my forearm bone to get it into place. Then I suppose I could key the IK solver as well as whatever bones I manually tweaked. Is this a bad idea? If I have to rotate any bones manually in the IK chain, should I key the constraint off ?

Thanks for any help, I want to start off on the right foot.