Thirty seconds to three hundred sixty-five days. There is no standard.
On a related note, if you are being offered a plea arrangement by the prosecutor's office, keep in mind this is a type of negotiation. Counter their offer and agree on something in the middle.
If on the other hand your defense attorney has made an attempt to reach a plea agreement with the prosecutor and the prosecutor has taken it, take it and run.
Either way, get it in writing (called a Cobb agreement) make sure it is signed, and keep a copy in a safe place. If the prosecutor or the court deviates from the agreement in any way, withdraw your plea and say nothing (stand mute).