Please help me plan my life out lol!

Ok... I’m 37 and have a 2.5 year old daughter. I love her so much and pretty much spend all my free time with her- outside of 5 days/week 9-6pm and grad school twice per week at night. I feel like I am able to do this right now ‘mom-guilt free’ since I know it’s bettering our future and my hubby is amazing with her and works from home primarily.

I am not imagining putting another one into the mix until I am done with grad school next year, I will be 38. After that I will ‘just’ have my job and a 3 year old. However, I would ideally like to have some down time between graduating and getting pregnant.

Ideally I would like to wait until my daughter is 4 (pre-school) which means I will be 39. My question is... would it decrease my fertility/successful healthy pregnancy odds to wait until I’m 39 vs 38 for a second?

For reference, my first pregnancy I was 34 and got pregnant our first cycle actively trying, but I know things change after a point...