Hard to answer, since you didn't say where you are. It really helps to put your location information in your profile, so it shows under your screen name, like mine does. It is hard to answer ANY gardening question without regard to location -- maybe why your post did not get a response.
So it depends on where you are and how much time you have in your season, whether your moonflower vine has a chance of blooming this year. But unless you are quite far south, I'm guessing probably not. Moonflower is a summer blooming annual. I actually start mine indoors a week or two ahead of my average last frost date, under lights. But you wouldn't need to. It could also be planted in the ground once the soil warms up. For growing indoors in container, supplemental lighting might help. I don't know when you planted yours. It looks healthy, but small. Starting mine in early April, I think it was early -mid July when it started blooming. Even though yours is indoors and will not get frost killed, if you are in a northern area, days are getting shorter, so it will be harder for it to bloom, unless you are giving it lots of extra light.
Mine is in the ground and with all the rain we had this spring and summer, it got huge. It went all the way up the shepherd's hook it was planted next to. So I started training it over to the next shephard's hook 4 feet away. It is now a solid curtain of vine between the two poles, 4' x 7' high and sticking out in all directions and covered in blooms. Remarkable, I've never seen anything like it. And it is fun, because the shepherd's hooks have bird feeders on them. So now the vine is full of goldfinches hopping in and out of it to get to the feeders that are almost lost in it.