In life there are lots of ways of doing things. Sure it would be nice if you could get the blessing on the rosary in person but the important thing is that you get it blessed. I feel that you getting it done in person is more for you while getting it done period is for your father (it is for your father, right?). Do what works out best. I could also throw in a guilt trip. Suppose you hold off getting it done so you can do it in person and then something happens to your father?