Usually, the first offer you get from the Prosecutor (on a slam-dunk case such as this) is the best offer you'll get (called an early disposition offer).
Once the Prosecutor 'gears up' for trial, yes, the offer is less. Most Prosecutors will still offer a plea (but, they don't have to offer any plea bargain, on any case).
Usually, the defendant's attorney will 'waive time' when the case is set for pre-trial (they have 45 days from the entry of your plea, to get you to trial). That takes the pressure off the attorneys - the trial will be scheduled later.
Most Prosecutors would love to try a case such as you describe - it's a slam-dunk guilty. They will expect you to try for a plea bargain.
Try to get a PD who will negotiate with the Prosecutor. If you're present, to beg, when s/he speaks with the Prosecutor, it usually helps (puts a face on the facts). If the Prosecutor will bargain, expect a ton of community service.
--Give the Prosecutor a reason to give you a break - remorse, squeaky clean record, going into the military (only if true - they'll check everything you say), heavy volunteer work in the community, why this was behavior different than normal.
Don't whine, though.
Dress well, speak fast (they don't have time to talk). Beg quick. If it's true, start with: I had an excellent, squeaky-clean record, until this happened; I'm sick over this. I'll do anything I can to keep this off my record.
Do not talk about the facts of the case with the Prosecutor, just the potential sentence. They can be a witness against you regarding the facts of the case.