OP, I’m not newly engaged (it’s been 4 years), but I can give you my opinion because I’ve had to postpone our wedding and re-plan parts of it, like the guest list and some suppliers who are no longer in business.
There is no point in starting to plan the wedding of your dreams for a while, in my opinion. Not being grim, just realistic. The venue and/or suppliers that you painstakingly work on choosing could go out of business. Your guest list is also worth holding off on- a lot of couples are having to create several guest lists in preparation for restrictions easing/tightening, which is such a headache. But our wedding is paid for almost in full so we have to go through this headache. You don’t yet.
I’ve sent the new Save the Dates after our wedding couldn’t go ahead this year, but I’m holding off on sending the new invites because we might have to UNinvite half of our guests!
A friend of mine has been going ahead with planning her wedding for the end of 2022, but she’s only paid minimal deposits and I think if you pay by a credit card, you might get your money back if the venue goes bust.
Something to keep in mind also is no wedding insurers are taking new claims, as far as I know. Those that do have quickly written in a clause that they won’t pay out in a number of cases to do with the pandemic.