Defoe left Tottenham and the Premier League to play under former Spurs defender Ryan Nelsen at the Canadian franchise and marked his debut with two goals against the Seattle Sounders.
While MLS is traditionally derided as a last payday for players from Europe's major leagues winding down their careers, Defoe hopes a prolific run can propel him into Roy Hodgson's thinking.
"(United States midfielder) Michael Bradley took the same decision," he told the Daily Mail. "He was at Roma but he wasn't playing much and he wants to play.
"At the end of the day you need to be playing regularly and playing well to get into a World Cup squad. You can't be at a club where you're not playing.
"Playing for a big club like Tottenham for all those years - nine years in total - is something I'm proud of but in life opportunities come along that you sometimes have to seize. This is a fresh start for me."
Defoe had fallen out of favour at Tottenham despite a good Europa League record, with successive managers Andre Villas-Boas and Tim Sherwood preferring Roberto Soldado and Emmanuel Adebayor in the Premier League.
"I think I scored something like nine goals in nine (European) games but I still wasn't getting the opportunity to play in the league," he said.
"There was nothing I could do about it, it's up to the manager if he doesn't want to pick me in the league, but I did spend quite a lot of time on the bench.
"Last season I scored a hat-trick in Europe and then AVB wanted to play Adebayor up front on his own against Man City. It was frustrating but it's partly because football has become all about the squad. I guess years ago you wouldn't leave out a forward who's scoring goals."