Posh sign young talent
Posh manager Barry Fry spotted the Scot in a five-a-side tournament in Derby during the summer and he initially handed Craig a week's trial with the Division Two outfit.
He has impressed in pre-season friendlies against Dagenham & Redbridge and Cambridge City but Fry was unable to offer the striker a deal because of the club's finances.
However, Peterborough were able to sign Craig when a Posh supporter approached Fry about sponsoring the striker's contract.
Fry told the Peterborough United official website: "I watched David play in a five-a-side tournament, which lasted all day, and the team he played for won and he scored 21 goals.
"He impressed me and I spoke to him afterwards.
"He told me he was unattached so I invited him down for a week's training.
"David was obviously out of sorts fitness-wise, so I played him in a few games during pre-season.
"At the end of the game against Cambridge City, a well-respected supporter approached me and asked me my plans for the lad.
"I said that because funds were tight at the club, I couldn't offer him anything.
"The supporter kindly offered sponsorship for two years and after speaking to David and agreeing a wage, he signed a two-year contract."
Fry sees Craig as having plenty of potential but his inexperience will mean it will be a while before he makes his first team debut.
The Posh boss added: "David has a lot of potential and hopefully he can fulfil it and turn into a great player for this club.
"We have got to give him time, he has the ability as he showed in the games, but we have to get him fit.
"There is no way he will be ready for the first team for another five months, but he has got a great opportunity coming in from the streets."