About three weeks, in my experience, but it varies and can sometimes take up to six weeks. Once, it took nine weeks, and we'd all decided it was lost, and TeeFury refunded my order. Then it showed up... in damaged wrapping. I blame the postal service.
You
might get them in time, but I wouldn't count on it.
I ordered my Frozen/Doctor Who tees (to Canada) in late March. They arrived in early April - while we were in Disney.
Still it was a nice treat to come home to!