Mining timelines in a long text
It looks to me like what you propose makes sense, but there has been some research done around these questions of time representation already. I'd suggest you check the state of the art in this domain, if only not to reinvent the wheel or miss important cases.
I'm not very knowledgeable about it but I can at least point you to TimeML and the related publications. There are certainly other recent works building on TimeML, for example this one (disclaimer: I know the author).