Adjusting flight time without a fee??? Any tricks???

I just got word that I need to adjust my booked flight to depart a few hours earlier the same day. It is for my small business and I am taking a few employees. This is probably the biggest trip of its kind my small business has made, so Im looking to save on cost since the business trip is already a gamble of sorts. Is there any tricks to not get hit with a charge to change my flight time by a few hours? The airline is continental and the flight is scheduled for next Friday. Tickets were purchased with Amex Gold business.

Thanks.