Training Plans in combination with IRL

Its getting cold and dark early here in NYC and my only chance to ride are the weekends (i work at a hospital and we are super backed up these days) so today I took my wahoo Kickr out of the closet and started the Build Me Up training plan. I have been riding for about 20 years and raced for a handful but I never really trained, i just went with the flow. Is it too early for me to start training? Not sure what I am training for to be honest, maybe to get my FTP up, get stronger for the spring? I ask if its too early because throughout the years ppl would always say that you don’t want to peak too early in the season and suck for the rest of it. Lol not sure how true this is.

Actually the main reason why I train is because it’s hard for me to use Zwift on the trainer without it. Outside gives me motivation to go fast and challenge myself and friends, if that makes any sense.
My second question is, if I do follow this training plan can I ever go outside and ride? Lol For example about a month ago I knew that there was 3 days of rain in the forecast so i took advantage and road gravel on friday, road bike on Saturday and ended it with mountain biking on Sunday before the rain came during the week. That is pretty rare actually but I do try to fit in a nice ride outside, 30 to 65 miles.
All that being said , i would still like to be stronger come spring, summer, fall.

When to start training depends on when you have any events or special rides planned for next year. I have started my winter plan already with the focus on my club spring trip mid March 2021.

In terms of combining indoor and IRL riding… I tend to use the outdoor rides in winter as headspace and fresh air with the indoor sessions focussed on training & targets.

I still use the trainer in the summer (dad of a 2 year old & wife also cycles) but use the outdoor rides for efforts and pushing myself with the indoor sessions to stay loose.