I am an SLP in Irvine, Ca who specializes in stuttering disorders.
First, please understand that many children between 2-5 stutter, especially boys. You should not wait and see if he outgrows it. Instead, please seek professional council by an SLP trained in fluency shaping therapy.
There are a few things you can do to help reduce the enviornmental demands and increase his processing capacities. Please reduce any open endend questions that require a lengthy response, and instead, ask close ended questions which require a yes/no response. Maintain eye contact, do not interrupt, and reduce any language demands and time pressure.
Check into local SLP in your area to get an evaluation. Any experienced SLP should be able to give you tips to help him with an indirect approach, or if the stuttering is severe enough, she/he may recommend speech therapy.
Feel free to call my work number at Coastal Speech Therapy ###-###-#### if you need more help.
M.