I make it until Day 5 it's hard haha.
Simple, challenging, and a good game, could have a big potential for improvement like adding sound effects, particle effects, try add a grab hand icon (or something similar) as a mouse pointer when dragging the egg, and lastly give an alert warning when the time (not the egg but the clock) is almost up so it gives the player feels more nervous (that will be interesting).
I wish there is a pause time at the beginning of each level before I start make the first move (something like a count down or similar), so that I have my own time to make my careful decision where to put. Because when it starts all my time is about the temperature haha.
For future improvement, add a simple instruction in the game at the beginning so the player will get overall context. Just an idea, maybe try a different color palette on each days (that's interesting). Add a heating or cold light (or an animation or something) inside the incubators box.
That's all from my feedback to your improvement, great job overall and keep making fun games!