I would presume this depends on your zone. I think most of the websites will only ship to you when it is appropriate for your zone.

In my USDA Zone 5, there would still be time to plant hardy hibiscus. The ones I have don't really emerge until late May early June and then they put on growth like crazy!

Because they are bare rot plants, they may skip flowering on the first season (if the roots are not treated fine) but, since this hibiscus has a long flowering season, it may eeek out a bloom very late, like in the Fall. Make sure that your temps will be adequate for shipping bare root plants though. The nursery usually stops shipping in June-ish but you can delay shipping until next year if shipping in May-June is too hot where you live. They will restart shipping in September but, if I were shipping late in the growing season, I would have to hang on to the shrub inside to protect from the cold... something I would rather not do.... so I would not place the order until next Spring.

The slipper ballet is not a shrub. It's a perennial hibiscus that dies completely back to the ground in the Fall and starts all over again from the ground up in the heat of the summer. I think you can plant now. Just keep it watered until it starts to emerge from the ground. Then you should be good to go!

Ok thank you, I already ordered it anyway. I was so anxious. I can’t wait to see them bloom

Post pics when it does! You are going to love it. They are wonderful plants.