I've had a couple BOS beers with Belgian Blond, and your recipe is very close to mine (I use 10% sugar). Your target of 23 ibu's is good, but if you err, go lower. When my ibu's got to 25 it really affected the beer's score.
I also use 3522. My fermentation schedule is to start it at 62°, and let it free rise to the mid-70°s. I just try to make sure it doesn't cross 70° in the first 48 hours, or the phenols get a little too strong. If it stays cold too long it lacks the esters that I really like. I also prefer mine quite dry, so I mash at 147-8°, and it finishes around 1.008.