When to panic?

I had a horrifying moment when I spotted a male German roach in my bathroom while getting ready for work this morning. The first one I’ve ever seen in our house. After a panicked google search I scoured all our baseboards and any areas I could think of that they might be interested in and found no other traces (no droppings, tracks, egg casings, etc). I rent a rowhome, which means I’m sandwiched between two other houses that I share a wall with on either side.

I just wanted to know… should I start freaking out and going ham on the treatment yet? Or since I’m not finding any other signs of the little bastards, is it possible this one just migrated from a neighbor? Either way I ordered some of the suggested supplies from the pinned and am gonna do some preventative cleaning/treatments. Everything I’m seeing keeps saying “if you see one, there’s definitely more” but I figured I’d ask before I go scorched earth and start harassing my landlord about an exterminator (especially since I doubt she’ll be prompt or helpful in that regard).

Any advice or reassurance is greatly appreciated, my roommate and I have been freaking out all day especially because we’re both pretty tidy people and this is like a nightmare scenario for us.