You can get the starters within approx. 5-7 minutes of play. Once you flesh out the quest and talk to your mom, it sends you off. Get your second pokemon and as long as you can pick up a friend code or local connection, you can trade. I got x2 of each starter my friend and I didn't have in about 20 minutes of play, give or take. I started over as I ended up being annoyed I could not get a modest fennekin and didn't feel like breeding one. So, restart forever.
Not looking forward to doing it for an adamant torchic. =*(
TL;DR - Getting the extra starters should take approx. 20 minutes for you and a friend. There's shit all to unlock; get your starter, talk to your mom, then buy a poke ball and once you catch a second pokemon you can trade. Super simple. GG Chespin, Fennekin and Froakie immediately.