Need advice - EBF weaning & back to work

The day after my LO turns 1 I have to go back to work three days a week. My MIL will be watching her. My LO nurses to sleep for her two naps and is EBF (doesn’t take bottles but will drink from a cup or straw cup). I’m worried about my MIL not being able to get her to sleep.

Any ideas on how to make the transition easier? Should we just start slowly weaning the naps using a cup once MIL is helping or should I start sooner? I plan to pump while at work so I can slowly wean as we go. If anyone has done this before I’d love any suggestions. Thanks!!