Oh it is, the law states that The United Kingdom will leave the European Union on the 29th of March 2019.
Tickety Tock.
Maybe for people who struggle to get their heads round it it does seem to be an event, however "Brexit" doesn't end on 30th March 2019. There then comes the rest of it, whether that is the transition phase through May's deal or the carnage of No Deal in the event of that happening. The only way Brexit does become an "event" as such is if it's boxed off by revocation.