Personally, I would do it over several days. From experience, Alk swings scare the daylights out of me, so I have always done my adjustments over a series of days.
Recently, I had gone too long without checking my Ca levels. Turned out, I ended up with my Ca going down to 360 while my Alk hovered around 7.0dkh (I keep my Alk around 7.8dkh and my Ca around 420). I took 5 days to get things back in check. I know I could have done my adjustment in one day, I just find it easier to dial in my maintenance dose over the course of several days.
Now that I'm rambling, the numbers say you should be fine. Would I move forward with that plan? I wouldn't. That said, I may be a little over cautious... Hah!