Any advice for a newbie in payroll?

My boss (hr director) usually runs payroll. She began after the payroll person quit. I (hr generalist) am going to be taking over in a few weeks following the resignation of my boss. We just found out so I only have one payroll with her before she goes. We use paylocity.

Before I begin, I have 3 trainings set up with our account manager (who is delightfully competent actually) as well as sitting with boss on payroll day Monday.

I’m really really scared. I’m also excited, because I love new experiences and learning, but scared. I’m scared of screwing up someone’s pay. Currently I do benefits, L&D, unemployment and leaves. So I work with deductions but never processed payroll.

Do you guys have any advice or words of wisdom to share?