when should I up-pot mimosa evo?

Depending on the amount of time you have to veg and the space you have. I would even transplant it into something 5 times as large if you were flowering outdoors. but looks like you want to flower inside so you could just stay in those pots if you flower now. but I agree with mouse. If doing one plant Inside and want to transplant would go for around 20-gallon.excuse my imperial system, lol. If you have a month or two of veg they could be 6 feet tall and hungry

40 is really ok pot size for outdoors, but all depends when they will go to flower. few months of veg more maybe would need bigger.