Sample Size Calculation for Bayesian A/B Testing with Continuous variables

I'm doing some Bayesian A/B testing and I need to work out an appropriate sample size in order to detect an effect. Unfortunately, there doesn't really seem to be much information about this out there (that I can find, at least).

Let's say I'm measuring a continuous metric, which is currently at a value of 100 in the control group. How would I work out the sample size I'd need to detect a minimum effect of a raise to 102 in my treatment group?