If you're an Ivy Division hockey team, you have to visit Dartmouth sooner or later. The only question is when. In this case, the sooner the better.

The Harvard hockey team opens its 1981-82 season in Hanover tonight against a team that has traditionally started slow, picked up speed after the holidays and played near-unbeatable hockey around tournament time. For the first time in recent years, the Crimson is getting that Dartmouth trip over early, and will have home ice advantage for the rematch, just when the Big Green are liable to be red-hot (March 6).

"It's had a lot to do with scheduling before, I think," says George Crowe, the Dartmouth coach, about the tradition of slow getaways. "We've always started against the Clarkson's and the Northeastern's--teams that have a couple of games under their belts when we don't. This year, at least we're both starting from the same place."

But Crowe will have the difficulty of preparing an untested team for battle. Gone are stalwarts like Bob Gaudet and Carey Wilson and in their places...question marks. For instance, freshman Chip Kuzborski will start at goalie, with both Gaudet and backup Jim Jankowski graduated.

"It's a young team, there's no question about that," Crowe says, "and replacing those guys will be a problem."

For once, Harvard is not top-heavy with rookies. Only three--forwards Scott Fusco and Greg Chalmers and defenseman Brad Kwong--are expected to make the trip. "It's a luxury we didn't have the past few seasons," working the kids in gradually," Billy Cleary says. "In the past we've had to go with the freshmen because we didn't have the depth. Now, we have some people and we can work the freshmen in."