The service schedule for the OpenStreetMap license change was announced yesterday. It will put the OpenStreetMap database into read only-mode between April 1st and April 4th, and then start slowly processing all non-clean objects, meaning objects contributed by the few users who have not agreed to the license change by April 1st.
We will pull a copy of the last available OpenStreetMap database export on March 31st, meaning that all changes to the OpenStreetMap database made up until then will go into our next render of MapBox Streets, which is scheduled for April 14th. After that, we are aiming for another render of MapBox streets by mid May. By then, we expect the impact of the license change on the data to be largely mitigated by remapping efforts.