I patented something at a large software company (a software invention). We used my commits (and their log messages) as my 'notebook'. The patent office had no

I patented something at a large software company (a software invention). We used my commits (and their log messages) as my 'notebook'. The patent office had no issues with this. I guess the only reason that might not be good for you is the lack of witness? At such a large company it would be impractical to forge the dates for me. Github would certainly be trustworthy as proof. Personally I think git is overkill though. GitHub lets you make SVN repos too and I think that would be more appropriate for your use.