There are many ways to have your portrait painted. I recommend Calling me to talk about your project. Contact me through the email and I will send you back my phone number. A Facetime call allows me to show examples of my work on my studio wall. Turn Around Time for a large format oil portrait may be several months.
 
If you do not have adequate photographic reference and do not live near me so that I can take it, You will need to engage a person well versed in portrait photography and sign over a one time usage For their photograph. Even family members must do this because copyright for artwork is something I take seriously. There are things to discuss. 
A sketch or 'study is much less expensive than more finished work and fits the needs of most people. The likenesses are good and many people see value in the artistic value of the spontenaity. 
Graham