If I had to do it once again from scratch, I would say no more than 30 minutes. The modeling has nothing complicated, the time-consuming part is drawing a nice shape using Bezier curves. Once this is done, you just have to "follow-me" around a 48 segments circle, detach the part witch will be the interface between the glass & content, model the meniscus, and that's all. The process is nicely described in this tutorial by Patrick Nieborg.
