Lacerte should have someone to hold your had through this first year. https://proconnect.intuit.com/lacerte/getting-started/ Please come here for questions, but also bug the hell out of the support staff assigned to you. We are just other users and many of us never did a conversion, or if we did it was decades ago.
I do know that once you convert to 2017, you should be able to process 2017 and be sure things match up. When they match up, go to Screen 3 and look for a check mark at the bottom of the first section - Converted client (proforma use only) Remove the check mark. This will allow for a more exact proforma process from 2017 to 2018. Especially confirm the depreciation and the state return.
Welcome to Lacerte. We hope you have many happy returns.