What’s the latest date?

I would be looking into my options now and make a decision in a week or so.

Call all your vendors first & ask what their policies are and how they are willing to work with you if you postpone. You definitely want to be ready incase you do have to make the decision to postpone.
Then I would say give it until 2-3 weeks before your date. Honestly I dont think it will get better by then. They are saying the worst is to come by mid April, according to some doctors. But I dont know for sure no one knows.
Do what you feel is best for you guys.

Follow up question. Does anyone know of any FREE invitation sites in case I do postpone. I want to send virtual invites the second time around.

Our date is May 3rd in California. We contacted our venue and due to the circumstances they were really understanding, they’re putting a hold for a date in October for us. Our stay at home order is currently until April 19th, we told our venue we will either keep our date by then or go ahead with postponing if there’s going to be an extended date for the stay at home order. I definitely would suggest looking into what options you have for a plan B.

You mean the latest to wait to postpone? If your date is May 2nd, then I would say do not wait any longer and postpone NOW. I would contact your vendors immediately and get a new date booked. They are filling up very quickly so the longer you wait, the fewer dates will be available. Not only will things likely not clear up by May 2, but your date falls within the no more than 10 people at an event window. With half your guests having to travel from out of town, I wouldn't expect any of these people to attend. I'm so sorry that this probably isn't what you want to hear

Being that you have a large number of guests out of town i would give it until the end of next week to make a decision. Definitely start contacting your vendors and get your options if you haven’t done so already