Dark at 6am; Labor Day?

So it is dark enough at 6am that I need to wear a reflective vest. Today was considered my tempo run. Warmup, 4 @7:45, cooldown. Started at 6am to beat the heat (even though it was ~66 this morning) and so I could make it to work on time. I have a hard time running slow (for me!). My warm up and cool downs were just only 30secs/mile slower than the "fast" portion. The fast portion was 15 seconds faster than needed. I can only assume that is a good thing. The problem may come this weekend with my 1st 16 miler, running slow enough that I don't overdo it by going out too fast. Have a slight hamstring twinge this week - and my right calf is sore at times (that is almost normal for me, but still annoying!). New 2130's are doing well still. Need to make sure I don't overdo it on those before the big race.
So - I did sign up for the Labor Day 15k down in Columbia. My 2nd 15k, but coming 2 days after my 1st scheduled 20 miler. Time won't be an issue (I hope I don't make it an issue, but I have a hard time with that too). But - the labor day I was talking about is my wife's due date with our first baby: December 1st. With NYC only 4 weeks ahead of that - we are both a little worried, especially with our friend's just giving birth 3-1/2 weeks early. So far there are no signs of early labor (as our friends had), so I am hopeful of the best. I have until Oct 29th to postpone my race for a year. I could always find another marathon somewhere (maybe Greenville!) if needed. I certainly don't want to risk missing the birth of our baby....there's no hesitation there.