Right now you can begin getting rid of a lot of your excess 'stuff'. An uncluttered house sells more easily because it makes the house look larger. You might want to remove (sell or give to kids) some excess furniture, also. Get your home ready for sale - repairs, paint, etc.
Then list it by June - a good sale time. If it sells fast you could try for a contingency on being out in February and in the meantime pay rent to the new buyers.
If it sells fast and that doesn't work is there a RV park close to work that you can stay until October when bad weather starts? Then take the RV a little south out of the snow belt and store it for a few months until January and perhaps move in with relatives/friends or rent an apartment for the few months of Oct to Jan.
Have an auction for your belongings being winter it will be the easiest and fastest way rather than garage sales. You could advertise big items separately.
If it doesn't sell fast then you'll have a big head start on everything and hopefully you can leave for someplace warm in January. You don't have to be around for the sale. Everything is done by fax nowadays. If need be, you could leave your RV in the warmth and you could fly back for any last minute necessities.
Start on making a schedule of Things To Do and you'll probably need to keep adding to it.
... before retirement and even though you still have the house .... set up your mail forwarding and get your address. Now you'll have your address for Social Security without having to re-change it. Then start changing your address on everything. Keep a list as you change them. Remember the magazine subscriptions if you have them. They take 6-8 weeks to change. Set up AutoPays on everything you can.
or.... retire Jan. 2019 and then start doing everything.. listing the house for a spring sale.
We did everything in a 3m time period. Best of luck to you and yes, right now it seems overwhelming but believe me... when you start doing everything you'll get such a 'rush' of excitement and it will be like lifting a big burden off your shoulders. Many full-timers have done it before you and somehow it all works out. You may have a few months of stress but it will soon be over and you'll be FREE!!