I agree that some people abuse the getting of the info early and that there is no easy fix. I just like the info a few minutes before the appointment so I can write it down while in my car then park and walk in the building without waiting outside the street entrance for a callback in less than ideal weather. I would never go to the room before the set time.
Best solution is for the agency to answer the phone right away and just giver the info. With one agency I use this does happen like clockwork 80% of the time...but with another they say "We'll check with the SP and call you back" NOOOOO! Then 10 to 15 minutes goes by before the callback. Sometimes the appointment isn't readty to go at the set time. One time (nice spring day out) I had to wait 40 minutes out front, but I sat on a bench. In winter this wait would have not been acceptable.
Anyway, outcalls to the house (for the single client) are good as if they are 30 minutes late (it has happened) then no big deal. As for not ringing the doorbell before the time, yes, I never had an outcall SP do that - though if early the driver usually parks in my driveway and they sit in the car until the set time - once they sat there 20 minutes.
Most funny outcall moments - once the driver spent the hour session parked in my driveway drinking beer and tossing the empty cans out the window onto my lawn. Another time the driver left to do other things, and when my session was over and the SP called him to come he was no where to be found. So she and I had a drinks and talked for an extra 90 minutes (not on my dime of course) until the driver appeared to pick her up. He had gone to a friend's house and left his cell in the car and lost track of time apparantly). I am happy to say I have never had an crazy SP visit my house in the GTA - they all were sane and professional.
