What does it mean to fly a procedure turn?
In my opinion, as soon as ATC clears you for the approach, the holding pattern at Buhrs is cancelled (i.e., is no longer required - 1 min. leg cancelled). Begin a descent to no lower than 2600  and turn inbound as soon as you are far enough north of Buhrs (remaining within 10 NM) that you can comfortably descend from no lower than 2600 to  no lower than 2100 after established inbound on the localizer. (I would plan to be reasonably close to 2600 at the point of intercepting the localizer inbound so that I would not find myself above the glide slope).  

Remain at or above 2100 until intercepting the glide slope and finish the approach.

As you have pointed out in your question, the "point," "type," and "rate" of turn is left up to the discretion of the pilot.  Since it is perfectly legal, and most importantly, safe to do a racetrack pattern (on the PT maneuvering side) and that is exactly the position you are in, this would be the best option.  

The fact that your approach clearance came shortly after you had entered the hold (when you were turning outbound) does not obligate you to go back to Buhrs and then officially begin the approach by turning outbound again (45 degree procedure, racetrack procedure, 80/260, etc.).

Just tell ATC you are leaving 5000 and beginning the approach.

From the AIM para. 5-4-9, sub para 1: