Testing a 48-hour follow-up rule on newsletter signups

I've been sitting on a pile of people who signed up for the paid newsletter, read the free issue, and then nothing from me for two weeks. Ten of them, give or take. This month I'm writing to every new subscriber within 48 hours — one short personal mail, no pitch, just a question about what they're stuck on. Too early to say anything, but I wanted to put it in writing before I decide it worked.