2011: First big competitors such as Litecoin start to emerge
there is never been anything "top" about a coin that copies bitcoin in my experience. not to mention that there are a lot of more important events that you missed from 2008 to 2011 such as first bitcoin transaction, the Pizza purchase with bitcoin, first price ATH, first big bitcoin bubble, first big crash. these last two are important since you are talking about ups and downs!
2016: Steam videogame platform starts to accept BTC
it wasn't the first so it is not important.
more important were the much bigger companies such as Microsoft to start accepting bitcoin.