With my first, I was hospitalised at 29w+6d, with BP of about 205/200.. They said I would have had high BP from about 22w.

With Ned, I went onto Labetelol (BP medication) from 16 weeks, because BP was 150/95...

So I'd say yep, it's possible to have high BP at 17w. But do check throughout the day, as BP goes up and down depending on what you're doing. I don't know whether it's best to take it first thing, only if you're lying down and hadn't got up yet.

I'd definitely be speaking to your ob about it, maybe they can put you on meds, including low dose aspirin and beta-blockers such as Labetelol, these will help.

Good luck.