Advance notice can be found at times in proxy filings. PRE 14a, DEF 14a, PRE 14c, DEF 14c. Also when there's a change in control you can find advance notice of them in SC 14-f1 filings. Easiest way to get them is to use secfilings.com where you can search for filing types. I used to do it daily. You have to sign up to search but only an email address is required; there's no cost
My posts are my opinion. Do not be influenced by anything you read on any message board website unless you can confirm it.