I have read numerous things Bout nic breaking down in plastic bottles, and same with pg/vg over time. It's not a rapid thing, but figured better safe then sorry. I will keep it in mind about evolving.
You said you would be buying more supplies next month? The stuff will keep in the original bottles until you eventually buy more glass. Steeping in glass is better than plastic IMO so I'd go with just enough glass for that. Order more glass when you know for sure what you will need. I got more glass than I ended up needing when I first started. I know someone who needed glass for their herbal holistic stuff so it went to use and I still have backups.