Wait Step Issuedeployed before specific date

I have a flow set up with a 3 week wait step between each email delpoyment. No problems with the first 3 email sends. I needed to go in and extend one of the wait steps in order to make changes on an email, so I changed it to a specific day another week out. Well, my emails just deployed after the orginial 3 weeks wait step, despite the change I made yesterday.  Can you not change wait step duration during a flow? why did this happen?

Please help!
Thanks!