You should already have entered a plea at the arraignment. The pre-trial hearing is to determine if there are outstanding issues (such as motions) before the trial.
If you need more time, you likely should ask the prosecutor for more time. In exchange for more time, you likely will need to waive the time in calculations for speedy trial. If there had not been too many continuances, the court likely will agree to a continuance.
Until the offer has been presented to the court, the prosecutor can unilaterally decide whether to keep an offer open. No one here will know what your particular prosecutor will do in your particular case.
If you not now have an attorney, it is not too late to find an attorney. If you have an attorney, you should be discussing these issues with your attorney.