The thing is, before Saint Helens first erupted, not the May 18th eruption but the initial March 27th eruption, there were no warnings. It just started spewing ash. Granted, it was small amounts of ash, but it was an eruption nonetheless. The harmonic tremors then began in earnest after the March 27th eruption.
Even so, there were hundreds of small earthquakes between March 16th and the 27th. I just don’t think we are there with Rainier.