Portland Discovery Tours vs Mailrun

[SSAtlantic]

We are arriving in Portland after Halifax and St John. I know we have to go through Customs in Portland, and was wondering how long it may take. We would like to do the mailrun, but it leaves at 10 am and we dock at 9, so not sure if we would make it. Our alternative plan is to do Portland Discovery Lighthouse Tour. Is this a tour we need to book in advance or can we decide that day?

Thanks