I think it's sensible to wait. Give her some time to get used to you and you to her. But yeah for future reference they should be fine. I mean there's always going to be exceptions to the rule like if your current piggy hates other piggies (Mine was scared of adult pigs. she'd scream and run, so we had to get a baby pig) But once you know your pig, you'll know what sort of companion would be best for her. Just as you'll find out what foods she likes, if she likes treats soft or crunchy (we had these guinae pig cakes and Acorah would not touch them till they were slightly stale...then she'd demolish them) and what brand of hay she likes best and so on.