Probably not...
If you started your Tamagotchi life cycle on Saturday, then it should have turned 1 on Sunday, and then it will turn 2 sometime today (Monday).
Your Tamagotchi does not literally age a year older exactly the same time you started it on Saturday.
Sometimes it will take a half an hour or even an hour or 2 after your initial start time for your Tamagotchi to turn a year older.
Just wait until tomorrow (Tuesday); if your Tamagotchi does not turn 2 by then, then you might want to return it.
BTW: Make sure you don't pause your Tamagotchi because that does effect the Tamagotchi aging/evolution cycle.