When To Start Watching Movies/Series In Your Target Language?

I have just started watching some series on Netflix and I do believe that once I have enough words that this will be a really useful method as I can just keep watching and reading and while doing this train my ears to understand, but now having just over 10.000 words I thought “yeah I will be able to understand quite a lot” and it is not the case I guess I still have another 10.000 words to go until I can really enjoy a series and know more or less exactly what is going on. But there are times within a series in which I can understand 100% but within a whole episode of a series I only really understand 20% at the top.

I guess I am just gonna have to keep grinding away at Spanish and get more of an understanding of the grammar!