I felt I was ready for a full when I finished a half and still felt like I had fuel in the tank to go further. I think you have a good base already. I’m not familiar at all with the pfitz plan but the plans I have done usually have the first long run be 6-8 miles and go up from there which is easy if you are doing halfs. I tried to get my base close to 30 MPW before I started but 25 should be a fine place to start from.
I’m not sure your goal of 3:45 is realistic with a 1:51 half. My half PR was 1:44 and the best I have done a marathon in is 3:53. You may adapt better to the marathon training than I did and add more speed through the race. Good luck!
I felt I was ready for a full when I finished a half and still felt like I had fuel in the tank to go further. I think you have a good base already. I’m not familiar at all with the pfitz plan but the plans I have done usually have the first long run be 6-8 miles and go up from there which is easy if you are doing halfs. I tried to get my base close to 30 MPW before I started but 25 should be a fine place to start from.
I’m not sure your goal of 3:45 is realistic with a 1:51 half. My half PR was 1:44 and the best I have done a marathon in is 3:53. You may adapt better to the marathon training than I did and add more speed through the race. Good luck!