Ferguson said that Assombalonga will continue to improve and become a player who can take League One by storm.
"It doesn't get much better for a new striker than scoring the winning goal on his debut," PA quotes Ferguson as saying.
"There is no doubt Britt is going to prove to be a great buy for the club. We saw that he is a real handful who will only get better.
"I'm really pleased to start the season with a win."
Peterborough were relegated from the Championship last season.