You will probably get 10 or 20 different suggestions, but if that were my nursery I wouldn't have asked anybody but would put one long rod over the windows to hang from them 3 or 4 panels of thermal drapes on ring clips. That way I could cover some windows and not others depending on the angle of the sun. When I wanted all the windows uncovered I would pull all the panels to the right, so I would want the curtain rod to be long enough on the right to do that.

Target thermals $25

Draperies across the entire wall on a single rod and stacked on the right.