First things first: Don't invest anything in equities that you don't plan on leaving put for at least 10 years. The next couple of months will by a tiny blip 10 years down the road. If you're looking to time the market and/or get some quick short term gains...well...good luck with that, don't risk anything you can't afford to lose.
That said, the next 1-2 months will be a rollercoaster. By all accounts of how things evolved elsewhere, the US is currently in the quiet before the storm. The US healthcare system is about to get absolutely slammed. More and more movement of people and goods will come to a standstill in 2-4 week waves as this thing progresses across the country. At least, this is the pattern we've seen elsewhere. People will die, entire industries will get decimated, but by summer it will have passed and we will be in recovery mode.
Are stocks a good buy right now? Well, they're certainly a better buy than a month ago. This is one of those rare buying opportunities that everyone talks about in hindsight but few actually pull the trigger on, because it's hard to take the plunge when everyone around you is panicking and everything is incredibly volatile.
To me this has similarities to circa 2011 when I was encouraging certain family members to purchase one of the many homes selling at deep discounts, but they wouldn't do it because "it's too risky" which then later quickly became "housing is too expensive" as things bounced back.
If I were in your situation I would wait about 2 weeks until we are deep in the throes of the pandemic. I would then invest with confidence for the long term. If you just can't bring yourself to invest all at once, then dollar cost average your lump sum over 1-2 months. Either way, you don't want to be holding lots of cash in this environment. The Fed will further drive down interest rates (we may even see negative rates) and will inject a shit-ton of liquidity into the system.