He started 11 games as a rookie, and I believe they were all consecutive, finishing the season as the starter. So not from day 1, but started starting game 6 and on.
For the first 5 games, the starter was either Kendrick Clancy, or Kimo von Oelhoffen. Kimo was originally used as NT and then switched to DE, while Clancy only lasted 4-5 years in Pittsburgh. Currently a Saint.
Hampton was a major contributor that season, though. Really bolstered the D-line.
Props to clover_jeez!