I was just labeling everything for daycare, and thought that I'd share these. We're required to label *everything* that goes with them (both DDs are in rooms with up to 12 kids, so it helps us get our stuff back).
We used these for our older daughter too and they stayed on through washing her bottles in the dishwasher countless times. Plus, so much cuter than using a magic marker and are mostly coming off easily now that I'm switching them for DD2's name. https://www.etsy.com/listing/126487205/waterproofdishwasher-proof-personalized
We also had these for their clothes. The seller took a while to get them to us, but they've also worked well. https://www.etsy.com/listing/154517566/115-custom-private-school-uniform-labels
PS. I'm not affiliated with either seller... Just passing on something that worked for us.
Edit: I couldn't handle copying two different links