8 weeks is a short period for a project(no matter how easy it seems in a project charter or design paper), it could take you 4... 8.. or 20 weeks depending on available time, resources, scope changes, etc. Go is an easy language to learn, but if you have javascript experience... and no C, C++ experience, I would go with what I know and leave learning Go for weekends or free time and then apply it.

That being said, IMHO, Go is better than NodeJs in almost every sense. So I wouldn't waste time and get to learn it asap, so you are ready for the next project.