A weekend night might work better for you than a Wednesday, but here's how I got ours going: talk to the pub management; they'll love the idea (or at worst, shrug their shoulders). It doesn't cost them anything! If they're into it, have them include your kilt night in their "events" listing, advertising, or website.
Create a flyer than can double as a mini poster. Hang one up at the pub, on library bulletin boards, at the local college/university, tattoo parlors, gun shops, wherever in public they'll get spotted. Any Irish import or Celtic-themed shops in town? Leave some of your flyers at these locations, too.
Your local newspaper probably has a free events listing service in their entertainment section. Submit your information there. Email the entertainment editor/beat reporter. He/she might show up at your first kilt night to take pictures and write a column about it (ours did!).
Finally, you can create a website to direct people to (here's ours: www.bingkiltnight.com), and don't forget to list your nights here on XMarks. Hope this helps...!