Good job Peter scraping is important.
What are you doing to be sure the bridge is exactly where you want it? Some people use pins. We create a pocket with a rabbit on the bridge perimeter.
You don't need to have any guide but be ready to be able to wipe away squeeze-out so you can see if it's located where you want it.
I would suggest though that you do a dry run using all the clamps you intend to use and then apply pressure to the clamps. While the clamps and bridge are in place use masking tape to create a "stall" like a horse stall on three sides. I use two layers of masking tape in front of the bridge and on the sides. I have the tape butted right up against the clamped bridge.
This creates a "well" of sorts on three sides for the bridge to fit into and not shimmy around on slippery, wet glue. It also verifies that the bridge is where you want it and takes the drama out of what happens if it's slightly off and out of place.
Just be sure when you slap the bridge down into the well that it's not sitting on top of any tape and instead within the horse stall that you made out of tape. After all clamps are set and snugged remove the tape which will go a long way toward glue clean up too. Never leave masking tape on a guitar finish very long it can eat into some finishes.
Now you have it in place and located properly. You also just went a long way in your journey to learning to use HHG for bridges too since you now have a method to quick locate the bridge without having to rabbit the bridge bottom and create a pocket.
There is a method to what I share with folks here by the way. 
Hope this helps and good luck this should be drama free and productive.