A second hair transplant, when to do it?

If at the 8 month mark I desire more density, would another operation be appropriate or should I wait until 1 year?

Since 95% of the growth (possibly not length but growth) occurs within the first 8 months, a second surgery can then be done if the desired goals are not met. By the 8th month, you will have a good idea what the value of the first transplant is.