Your plan sounds good to me. I'm also 63 and I am riding again after being off of bikes for 40 years or so. In that respect you are way ahead of me. I don't have a trainer but I have good enough weather to allow me to bike every other day. I track my progress with an app called "map my ride". I went from 6 miles/day averaging maybe 9 mph to now doing 15 miles/day averaging ~ 14 mph. I bought the bike I have now 4 months ago and that is when I started.
In my case, I am gaining strength and stamina on each ride.
I guess what I'm trying to say is that "you have a good plan and you will see progress at each step of the way. I think you will be ready for the road come spring so keep it up".