Nice job Purba! I think you set it up right… but a couple of comments:
1. the ICC is pretty strong (0.3), so you might also examine an ICC of 0.10.
2. the effect size of 0.3 is pretty strong. If you anticipate a 5% decrease in systolic blood pressure, for example, and the average SBP is 150, then this would be an effect size of 5/150 = 0.033. Maybe a decimal point error? You might re-check this one. I think for a pilot test a 5% reduction is pretty aggressive… it would be reasonable to power the study for a 10% reduction to accommodate the limited sample size you will have.