The 26-year-old signed a pre-contract for the Paisley men in March, but despite training with the Buddies for the remainder of the campaign and even featuring in bounce games, he was unable to get any competitive match time under his belt due to a red-tape wrangle.
But with Saints due to report back to their Ralston training ground on Thursday, Guy is determined to make a sudden impact with Danny Lennon's men, and he has never been hungrier for a new campaign to begin.
The benefits he'll reap from a six-day Spanish training camp this summer have only emphasised he made the right choice moving north of the border.
Guy said: "I think one of the things that really impressed me about St Mirren was the whole structure of the club and the facilities.
"I know the club sold the old Love Street ground a couple of seasons back and a lot of clubs would have used money left over from the building of a new ground to bring in big- name players.
"But St Mirren invested it in their Ralston training ground and the Youth Academy and you can see that is paying off with young guys like Kenny McLean coming through.
"To be looking at a trip to Spain pre-season is another huge plus given the climate in Scotland and it just shows what a professional club St Mirren are.
"The opportunity to train twice or three times a day with the sun on your back can only enhance our preparation. Plus the time away will bond everyone even closer for the campaign ahead.
"I would say I am as excited about this pre-season as any I have undergone."
Guy is straining at the leash to get going, and is desperate to hit the ground running as the Buddies aim to kick-on from last season.
The former MK Dons man added: "I have been counting down the weeks until the beginning of pre-season and can't wait to get going again.
"Obviously it is also a huge help that I know Tommy Craig, having worked with him when I was at Newcastle.
"So I have kept myself in really good shape over the summer as I am determined to really hit the ground running when we start back on Thursday.
"At 26, I feel I am coming into my peak years and I am really determined to make a go of it in the SPL next season."
Guy added: "The chance to test myself at the top level in Scotland is just what I need to kick on at this stage in my career.
"I am confident that Danny Lennon and Tommy Craig will get the best out of me and even at 26 improve me another 10 per cent."