There's basically no shot of this impeachment passing after the investigation is complete and a pretty small chance it would pass now. But if you wait, you lose the opportunity to grandstand. By doing this now, MTG gets to position herself as the only person willing to step up and do something while everyone else just sits on their hands. And she could have achieved her goal if it weren't for these eight GOP representatives who probably don't even like Trump enough. It's all symbolic posturing anyway, because even if her impeachment passed the House, it's dead in the water in the Senate. So this is just never going to happen.