Went 5 months between dispalcement/furlough. Was a little nervous to get in the sim. Hadn't flown in a while, new airplane, new company. Like the other guys said, it comes back pretty quickly.
I have on occasion had vacation periods between 3 weeks and 6 weeks. I brain dump alot on those. When I come back after those, I feel like I'm in outer space for about the first 10 minutes of sitting in the airplane. Plus all the Jepp revisions that need to be done, arrgh.