so my daughter is almost 6 months old and I am considering going back to work soon. I am breastfeeding and was wanting…

so my daughter is almost 6 months old and I am considering going back to work soon. I am breastfeeding and was wanting to get a good supply saved up before I start looking for a job. my only issue is dating it. I have little plastic viles made my medela that I have been using and on the box it said that you can write on them but I'm confused as to whether or not you can wash off what you write to reuse them and I have sense thrown away the box. I was considering getting stickers to date them with but idk if that would work either. any advice?