Resources for trigger based nurture/drip campaigns

Hello! We are newbies to Marketo and looking to set up a trigger based email nurture campaign. It will be composed 4 emails with the main CTA of reading a blog, checking out a landing page, etc. I'm hoping for some resources on best practices for wait times, etc. So if someone downloaded a PDF on the first email, do we really want to wait 5 days to send them the 2nd email in the sequence, etc. Any help or resources would be appreciated!