Hi- A small amount of Japanese stiltgrass can be hand-pulled or dug out, ideally before it sets seeds (which has occurred already this year). Japanese stiltgrass is an annual grass. It will die on its own at the end of the season, but seeds will persist in the soil to germinate next year (and up to ~5 years). https://extension.umd.edu/hgic/topics/japanese-stiltgrass
Advising you on lawn weed control in Montgomery County has gotten a bit complicated because of Montgomery County's pesticide law which the Court of Special Appeals of Maryland ruled in favor of. They upheld the law restricting the use of pesticides on private lawns and childcare facility grounds.
So I am sending you to your county's lawn care information, https://www.montgomerycountymd.gov/lawns/.
As this is a new law, the details of how it will be carried out is still being decided upon.
Synthetic pre-emergent herbicides cannot be used on Montgomery County lawns to control weeds.
Read our page on Lawn Weed Prevention and Management,
And our information on organic lawn care, https://extension.umd.edu/hgic/topics/organic-lawn-care.