I started running kind of late in life but have done 5 marathons so far. In my last race I finished in 3:17 which was good enough to make the podium in the 45-49 age group.
I'm training for Boston right now but will be lucky if I can finish in under 4 hours. I'm having a tough time with winter training in Minnesota.
At 30 miles/week you should be able to start marathon training any time. Most people seem to run 40 or 50 at the peak of their training. My
PR race was the result of a plan that peaked at 70 miles/week. Btw, I'm also on Strava and hope you don't mind that I just followed you.