Looking for best practise for local and server data handling

I've developed an android app which stores information about your courses in university. All data is stored locally in a sqlite3 database. I want to expand the app and make it possible to share those course information between two or more users, so they can edit the same course and its information. The aim is that on both devices the course will be synchronized. For this purpose I have setup a nodejs server with express (restful api) and mongoDB to store everything on the server.

My question is: What is the 'best-practise' for such a situation? Should i drop the local sqlite database and always get the data from the server when i start the app? Should i keep the local sqlite database and always synchronize it with the server mongoDB? Should i drop the local sqlite database and cache data from the server until the server tells the app that it has got new/changed data?

I'm pretty new to web/server development.

With best regards, Tak3r07