Lamar said before todays game that he would be "stunned" if Upton wasn't up by early August. So that still seems to be the target date right now.
My guess is that if Cantu plays well, then they might as well just release Rey Sanchez. Since both are right handed bats and Cantu can play more positions (2B,SS, & 3B), not to mention he is younger and has some promise to him. But if Cantu doesn't impress Piniella then it's a toss up between Sanchez and Fick. If that happens I still think they go with releasing Sanchez because Fick has been playing better and is a left handed bat.