my step uncle died without a will and have a brokerage account of about 48,000 dollars between cash and stocks. If my step father request to be voluntary administrator, how long would it take to be appointed and can the value in the account make a difference on using the small estate affidavit form?
Since the account is over $30,000 in value, your step-father must file a petition for "full" letters of administration. He cannot use the small estate affidavit form. Preparing the petition would take very little time, but the proceeding would have to go through the court process and it is difficult to gauge how much time the court will take. Another factor which may increase the time involved is whether or not there are other interested persons that are entitled to notice.
If your step-uncle had other siblings besides your step-father, they would be entitled to notice in the form of a citation or they would need to sign a waiver and consent form. Below, I have provided links to additional information on the subject.
This answer does not constitute legal advice and no attorney client relationship has been formed. Before choosing a course of action, it is always advisable to seek the advice of an attorney in your area.