I'll be interning at a whore house this summer and I've been strongly advised to learn Excel VBA and perhaps C# for backtesting. Unfortunately, my current coding skills leaves much to be desired as I can simply dick around with Python. In order to get up to speed with some programming I've decided to take an 80% course load this semester to focus on coding during my spare time, in addition to taking econometrics as I believe it would give me some grounding on basic time-series concepts which may be quite beneficial for me. However, I haven't used Excel in ages and I'll have to learn both VBA and C# (object oriented, vastly different from Python) from scratch.
Hence, I've set a goal to refresh some of the key concepts in Excel and learn VBA in under two weeks, hopefully giving me adequate time to also learn C#. What are some of the most efficient resources that I can use in pursuit of this endeavor? Any advice would be much appreciated.