I got weeklies up til 11 weeks, but I have had a previous molar pregnancy, so hCG level testing became something of a hobby of mine. I loved it - they put my mind at ease even more than our first scan did.

I'd say to ask for at least three, then you can choose how far apart you get them. Google "hcg doubling rates calculator" and it will give you a rate; I found this SO useful.