According to the Maryland State Board of Elections website 11,580 votes were cast in Howard County on day 1 of early voting (October 26th). Here is the county by county chart: https://elections.maryland.gov/press_room/2020_stats/EarlyVoting%20by%20County%20-%20PG20.pdf
Here is the breakdown by councilmanic district: https://elections.maryland.gov/press_room/2020_stats/EarlyVoting%20%20by%20Councilmanic%20District%20-%20PG20.pdf
In 2016 on day 1 of early voting Howard County voters cast 8,518 votes: https://elections.maryland.gov/press_room/2016_stats/PG16%20EarlyVoting%20by%20County.pdf
I will continue to track and report this data on the blog as the data is released by the state.