Seriously, though, most training plans assume you have some level of fitness and are already at some base training level before you start (e.g., it might assume that you are working out 6-8 hrs/wk with a long run of at least 60min and long ride of at least 2hrs). Find out what your plan assumes and work on getting there between now and then. If it's not clear, just look at the first few weeks of the plan and try to get yourself to the point where you'd feel ready to jump into those weeks immediately.
Enjoy these last three months of unstructured workouts. Now is the time to make adjustments to your swim stroke, bicycle, etc.
(My "maintenance" plan kicked in 3 weeks ago and leads me up to the start of my IMCDA training in February. It seems like most of the workouts are <1 hour, so I'll be adjusting it to keep a 2 hour ride most weeks and a 80-100 minute run. )
If you are looking for something with a little more structure or that focuses on a weakness, there are several winter maintenance plans available here on BT. Just click on the program button at the top and you can look down through all the training plans.