If you've bought it in a pot then its fine to plant it now but you'll have to wait until next year now for it to bloom. I love these and have several and they have all finished now. Good luck!

I presume it's not a dormant one like you get in the poly bags in poundstores etc. If it is I'd pot it up to establish before planting out

If it's in a pot with shoots already then I see no reason why it can't go out now.

The one I have which was in the bed overwinter has only just appeared in the last few weeks, with no sign of flowers yet.

Whatever you do protect from the slugs - they decimated mine in mid flower last year.