I think tomorrow should be fine, especially if it's just traces.
DS2 had blood in his poo at 8 weeks, it was an intolerance to the cows milk protein in my diet, I was off dairy for a few weeks & then it fixed itself. Or can be from a tear, as MR said, maybe something going on there if it's a bit mucousy...
It's worth getting it checked but I wouldn't stress too much overnight