With the shortage of installers out there these days (dam oil rigs!) any installer or shop will be booked a week or two in advance - as is any other trade out there that has good people (IE look at getting a house built these days around here). My advice, don't try to get it rushed, cause no matter who does it, it won't be 100%. See Auto Expressions, Visions - Blair, Audio Express - Tristan, AW/PA - Marlin... Not sure who PA Soundworks has these days intalling..
I'm sure someone may accuse me of being biased as I am a rep.. but hey, I'm gonna try to sell to good guys.. Note I'm not selling anything to Visions, AE or PA soundworks right now that is 12V - BUT I should be

!!! So there is some proof.
Good luck