Hello There,
                We want to have a following scenario..
   1. We have a set of users who are
 EXPERTS.(Whom we set as a Bookable Item)
   2. We want only those Experts
(We can give access level and user group for this set of people) to 
login from front-end and set their profile, photo, and their available time in our site instead of admin doing this.
(Admin may not know that EXPERT s availability time)
   3. The profile set by the 
ExpERTwill list  just like a bookable item list in the front end. Check the screen shot here.
        
awesomescreenshot.com/00822u0i6a
   4.  Now the customer can login and book this EXPERT from the list and Book him some services (Video consultation with the Expert / etc)(
How ever this is a normal process )
Regards:
Prasanna