Stock up now while no-one is panicking yet. Don’t waste money buying weird stuff - Just get stuff you’ll use anyway over the next few months.
That's what triggers panic buying... It's a snowball effect.
Socially, you're probably still better off buying sooner rather than later, because that means the system has more time to restock and ship things around for people later. If you're part of the end pile up, you're another stresser at the worst time.
As evidence of this... the ideal time to stock up with emergency supplies was months or even a couple of years ago, when it would bother nobody. I've buffed up some supplies a bit, but I wasn't starting from scratch because I've been keeping stuff on hand for a while now. Giving the system months or years of headstart is better than weeks, but weeks or even a single week is better than nothing.
Masks is slightly different I will agree. They are genuinely in short supply and medical workers need them more.
I speak from experience preparing for hurricanes. If you wait until the last minute, you're going to be woefully unprepared.