IMO you want to keep your temps no higher than 80F, they will survive short periods of around 90F, but if you keep your temps to 80F you've got a bit of room for normal temp fluctuations, like when there's a really hot week. You need to sort out your fan and see what the temps are like then, you might be surprised at how effective your fan will be at cooling your box, until then just use the two lights. You need to start thinking about the next phase of your grow now tho and ideally get it set up and tested before the plants need to go in. Soon you're gonna have to move your plants to bigger pots, they're not all gonna fit in that tiny box and you're gonna need more lights.

Good luck!