How long to wait for a VBAC?

I had a csection with my daughter due to what we thought was a herpes outbreak, it turns out it wasn’t but they didn’t get the results on time and I was in labor. I would really like to try a VBAC with my next child so my SO and I decided to start trying again at the end of this year or in January of next year. I was told it’s best to wait 18months to try a VBAC. I will be about 17mo pp in January 2019. Do they mean to wait 18mo to get pregnant or 18mo between deliveries? I want my kids close together in age and was thinking about starting trying a little sooner, as I’ll graduate college in June 2019 we want to have our next any time after that. When would be okay to start trying?