I believe there are codes for the DS in the "Tamagotchi Codes" section. You can look at your v3's instruction sheet (bottom right hand corner) for another code.
The Tamagotchi Connexion v4 matures faster than other Tamagotchi. Here's a list of milestones throughout your Tamagotchi's life. You might find your Tamagotchi evolves at a different rate to the times below, especially if you've been pausing your Tamagotchi. Even setting the time so it goes to sleep instead of pausing might also stunt growth and work times.
Hatchment: 1.5min after setting time.
Child: 1hr after hatchment.
-Preschool begins one hour after evolution from baby-child.
Teenager: 24hr after baby-child evolution.
-School begins one hour after evolution from child-teenager.
Adult: 48hr after child-teenager evolution.
-First job offer is 24hr after evolution from teenager-adult.
-If you do not succeed in your first lot of job offers, or if you exited the job offer screen, you'll get another lot of jobs about three-five hours after that.
-The matchmaker's first visit will be at either 10.30am, 3pm or 7pm. Your Tamagotchi will have to be in the adult stage for at least 72hr before the matchmaker will come. To summon the matchmaker, set the time to 10.29am, 2.59pm or 6.59pm- if your Tamagotchi is old enough she will come. However she only comes for ten seconds, so be on the lookout.
Senior Tamagotchi: Unsure, maybe about 150hr after teenager-adult evolution, if your Tamagotchi isn't married. As an old timer the matchmaker will stop coming. You will be able to mate by connecting with another senior Tamagotchi of the opposite gender.
-Your Tamagotchi will retire from its job when it is a senior Tamagotchi.