If you think you may install more cameras than those three, and this is the one shot, for easy access then you pretty have to run all the wires you may want to run.
I would start by evaluating the layout of the house, garage/carport and garden (fence, gates, plants,...) and see which are the best angles, whether you can easily reach them (don't know if you have roof overhang) and then decide whether you'd want 5 or 6, let's say, that depend on the remodel to easily wire a camera. Also map out the point where you will put the POE switch and/or DVR/NVR/...
Then reevaluate a couple days later. Visually inspect from outside. Double check practically about running the wires.
I know in Europe they use tons of the flexible conduit pal251 mentions. I don't have much experience with it myself and figure - for me - for the cost and labor of getting that stuff, running it, securing it, terminating it and then later push/pulling wires through it ... I'd just run Cat6 cable as needed to where all the cameras will be mounted. Reserve the conduit stuff if there really has to be later wiring phase; or maybe have some strategic wire chase pipe (but you still need to have neat access in/out). I think one is just better if you can avoid it. Get a bigger box or extra box of wires and run the wires end to end.
Don't know if you have a basement or if you are on slab. While you're at it, evaluate whether you may want network, cable and/or phone jacks in some rooms. If no basement, then now's the time if you want to double up on cable lines, add network points. A lot of people just want to use wifi for this and that, or everything; but personally nothing compares to interference and latency free hard line ethernet. I've got slow broadband with multiple wifi access points (elongated layout) any hardwired machine does anything network and internet related in a fraction of the time. Anyway. If you have thoughts about maybe having a NAS and distributing some photos, videos, ... take that into consideration. Look into needs & wants beyond just phase 1 with 3 cameras. Also consider if it is the time to possibly add a 110 line in some place or another. Then start running cable.
Also, since you are redoing ceilings. I've had to crawl into several low ceilings as well and dealt with some even a cat would have trouble with. You still may want to see if you can put a scuttle hutch in a closet maybe at the tallest part in the roof. I had to do one at a property two years ago to deal with an ac repair and duct replacement primarily. You can only stick your head and shoulders up above the rafters, but it was fantastic for visual inspection, running new ducts and a couple electrical lines. Nobody knows it is there really, and you have to empty the closet to get the step ladder in. But it was the most practical future proofing element, just in case. Then possibly, depending on the closet, that could even tie into being the location where network wiring comes together to the network equipment, etc and becomes the network a/v distribution point.
If you are doing that extensive of a remodel, look at any wiring you may want to or need to do for extra outlets, audio, video, cameras, ... Which may push your ceiling project back some. But such is remodeling, do it and plan it while you can.
Just food for thought. Practically speaking.
