I started Duolingo Spanish on May 5, 2015. Below is a chart showing how often Duolingo awarded me different fluency estimates. I do at least one lesson a day. I hope this data is instructive for other students. The code for this page is available for you to use on GitHub. - MAS
If you are learning a foreign language and would like to learn with a native speaker, check out iTalki. I’ve been using them for a year and it is a great service. Use my link and we both will get $10 credit after you schedule your first lesson.