This is a good question and one we often get this time of year when the next season is quite a long way off. What you can do is to start with a Maintenance Plan for the weeks leading up to your Peak Performance if you want some guidance now. This is a scaled back version of the racing plan and will get you going with training without the risk of overtraining or getting to your peak too early for your main goal race.
What will be important during the Maintenance and early part of the Peak Performance is going to be for you to do some kind of faster efforts occasionally, say every 3-6 weeks. These can be running races like 5-10k events, time trials on the bike or a swim race. Basically when you are doing your base work and off season work your training effort will be in the aerobic training zones. These are important to build so that later when you get to your speed phase you will have the physiological base to handle it. One way to boost this fitness is to actually do some anaerobic efforts that are not done on a weekly basis like when you do indeed get to the speed phase of training. These occasional efforts will sort of shock the system and actually bring all your fitness markers up both the aerobic ones and the anaerobic ones.
I hope that helps. We look forward to working with you!