What is the first thing I should do after purchasing?

Four things, in order. First, complete your onboarding, it exists to set you up right. Second, read your welcome materials so you understand exactly what your product delivers and when. Third, get your tracking ready, even a simple notebook beats memory. Fourth, and most important, plan your follow-up before the first lead arrives. Decide when you will call, what you will say, and when you will follow up. Leads reward the prepared. Be ready before they show up.