No matter who we play in the first round, we don't NEED Shaq. None of those teams can hang with the C's, Shaq or not, if they are playing with normal playoff focus.
With that said, having those games to get a rhythm for later rounds would be immensely valuable. I think Shaq is a guy who can just step in there and be effective because of his size, but everyone will have a better rhythm, if they have a few games with him in the lineup before having to face Miami in round 2.
No matter what though, I hope tonight convinced them that they cannot put Shaq back out there without practicing first. I don't want to play doctor, but I imagine the fact he went from 0-100 so quickly tonight played a role in that muscle injury. So, no matter when they bring him back, I hope they will ease him back a little better, rather than throwing him into games (particularly playoff games, where he would be going especially hard) without building him up a bit more to it.