I ordered several last year (although not antique varieties), and had them shipped at the end of May. I'm a rose newbie, so I can't say that's the best time, but mine sure did well. Several bloomed that first year.

I order mine to come in mid-April because I get own-root very hardy varieties. The frost is just out of the soil enough to plant within a week of that time and you don't wind up heat shocking them as can happen with our extremely variable May temps.

-Marie

Thanks so much for the info. all mine are own root, so I'll probably go for an April date!