Did Frodo and Gandalf actually meet before Bilbo and Frodo's party?

[Ibrîniðilpathânezel]

It's possible. Bilbo would have been a child (not a baby) at the time of the Fell Winter, when Gandalf "came to the aid of the Shire folk." I suspect, however, that any meeting that might have occurred would have been brief and comparatively insignificant. At the time of The Hobbit, it's clear that Gandalf had been observing Bilbo for some time (particularly from what I recall of the tale as told by Gandalf in UT). That Bilbo actually remembers the fireworks Gandalf made for the Old Took would mean that there was a possibility that they had met at some time prior to TH, but again, I suspect the meeting would have been casual, at best.