Thomas, who only turned 18 last month, made his debut in Tuesday night's 2-1 defeat at Northampton in the Johnstone's Paint Trophy and relished the opportunity.
He told the club's official website: "I was chuffed to bits when I was told I was going to make my debut. Eddie Howe and Neil Moss (goalkeeping coach) told me I was playing in the morning and I was just buzzing after that."
He added: "It was a great day for me and I know that not many keepers of my age get a chance so early in their careers.
"I played for the youth team on Saturday, so to go straight in to the first team was a massive step, but a great experience."