Congratulations, you did it!
Is it a boy or a girl? I still have trouble telling from the underwings. It's easier when you can see the upperwing coloration.
Butterfly wings are fragile when they first eclose. They pump fluid into the veins which form the "umbrella ribs" if you will. They also usually "splat" -- there's an official term (that's not it
) -- and excrete excess fluid when they're done. With Monarchs the splat is usually bloody red, and scary for first timers.
Don't worry, the butterfly will know when it's ready to fly -- depends on temperature, sun, humidity, etc. I like to put a bouquet of different flowers in the cage so they'll have a choice. Typically, they prefer flowers that have lots of tiny flowers on a stalk. Lavender and mint, and clover are usually popular, as are daisy family flowers like cosmos, zinnias and asters, and of course, butterfly bush. I also have Summer Sweet that get high points too.