I'm planning on running in the B/CS Marathon this coming December and am looking at what an appropriate goal may be time wise.

I ran the Irving Marathon in 2013 and finished around 3:48 or about 8:43/mile. I've ran off and on since but mainly 5Ks and haven't pushed myself like that in a while, however I'm running the San Antonio 1/2 next weekend and thinking I'll end up just over 9 (haven't been as diligent until lately in training for it). I want to use it as a spring board and gradually build up strength for the end of the year. What would be a reasonable expectation? I'd like to push close to 8:00. Is that expecting too much?

i honestly have to say, there are too many variables to give you a straight answer.

need to know more info. any other relevant race times? what's the plan between now and the race? how'd you feel after that 3:48? what kind of training went into that first race? have you gained/dropped weight since then?

Really too far out to know. Use the 1/2 as a guide to set your current training paces and then run other benchmark races between now and December to adjust your marathon pace. You probably know this but if you want to run a marathon at 8:00 pace, I'd expect a half marathon to come near 7:20-7:40 pace.

Yeah. Maybe I need to do a half early in the fall. This half isn't going to tell me much unfortunately. I've lost some weight over the past few weeks but really wasn't focused to start the year. I feel like I could've done better in my full cause an injury knocked me out from doing lots of the long runs. I was also 4 yrs younger I guess.