Welcome Alex. I second MJ, your solo should be a low stress surprise. It has worked out for the best for you. Ask your instructor to tell when you're going solo, when you have just landed, and not before. It'll really work out better for you.
We all have days where we are not up to our best, your instructor put you on hold - perhaps the best for you. You'd rather be unhappy here today, waiting for a good first solo, than looking at an unhappy plane right now, and your first solo being bad. It'll come.
The second time I went first solo, my instructor did tell me the day before, and I really sweated it.
Hang around here for some great support in the long term. In the mean time, don't worry about solo, it'll happen fine, and for the rest of your life, you'll look back on a success and bit late, that's all - focus on the success you're going to have.....