Notice of tenant moving - timing question

[Dan O'Neill]

Hey fellow landlords, need some opinions/advice.

I have a tenant on month-to-month.  The lease requires 30 days written notice to leave.  I got a text Mar 4 that she'd be moving with no date indicated.  After speaking to her, I got verbal notice that she would be leaving end of April.  She had been sending me text updates and as of Mar 23 via text we were still on April as the final month.  Fast forward a week and she's gone and doesn't want to pay April and I'm left with an empty unit for the month.  Thoughts?