My experience may be somewhat dated, but I was sponsored by my wife in late ‘06 and started applying for jobs soon after getting COPR... As I recall, I had one interview before landing during which I explained that I would be landing around X date. I ended up having a second interview with this company/same manager after landing, and was offered a position. All other applications pre-landing resulted in radio silence.
In retrospect, it wasn’t a bad option, certainly better than completely waiting until after landing. I think I could have clarified my eligibility to apply better, more clearly noting that a COPR had been issued and that I intended to land on X date- but even that isn’t great because hiring officials may not be confident to waste time on the unknown.