The former Sunderland captain said: "I have to adjust and hopefully in the coming weeks we will get to know each other's game.
"After two, three, four games you're ready and raring to go. I've done most of the running and stuff, but that was my first game and so I'm playing a bit of catch-up.
"I played 60 minutes and hopefully I'll get another 60 at Nottingham Forest on Wednesday."
Whitehead, whose transfer could end up costing Stoke £5million, is confident he can help the club survive a second successive season in the top flight.
"I've played 100 games in the Premier League, so hopefully I can bring a bit of experience to a group of players who had a good season," he added.
"It was a fantastic season to finish 12th and there's no reason why we can't do better than that."