Re: When do you put your plug in?
Mine goes in at the ramp and comes out at the ramp. That's the way everyone I've known who has a boat does it, and it makes sense to me. My boat sits outside under cover, and after a heavy rain it will be a little wet inside in spots so it's best to let it drain. Heaven forbid the cover got torn or blew off, the boat may fill with water!
My launch procedure, more or less, at home I run boat on the hose up to temp, check fluids, uncover, clean anything that needs cleaning, ensure I have safety equipment and watersports gear, lines, bumpers, etc. check straps/winch/chain, check lights. At ramp I remove transom straps, insert plug, prep dock lines and bumpers in prep area. Then back down ramp, remove chain, start engine, release winch/cable and back off trailer.
When I pull boat out I winch to stop, attach safety chain, pull out to de-prep area. Then stow any lines/gear/bumpers/etc., pull plug, reattach transom straps, double check winch/chain, check safety chains, plug lights in, cehck lights, go home.
Once home I run on hose for 5 mins or so (up to temp) while I clean up boat some more and start putting cover on, then shut off, finish covering, hose off hull/outdrive/trailer (I launch in brackish).
That's more or less my routine, but bottom line is boat is always stored with plug out. Every summer I go up north to my grandparents summer cabin on a lake. This year I was first up there and opened it up, picked up boat, etc. When I picked up the boat form the place they store it the guy who stored it had uncovered the boat and left it outside expecting me to pick it up (in case he wasn't there) but left the plug in (didn't tell me this). When I got there it was pouring rain for two days before the sun came out so I didn't pick up the boat 'till after that, and found it full of water halfway up the engine and above the floor in the rear. Took forever to drain and everything was soggy and wet. Perfect example of why I leave the plug out on my own boat. Grandparents boat stays in water all season though (fresh water) so plug only comes out for winter storage (if ever).