Tl;dr: You could place them on the market now, but that doesn't mean you don't have any work to do now.
You may want to be careful about a couple things (incomplete list):
- The end dates of the various transition periods: different provisions of the IVDR will be enforced before the final deadline, so you may want to double-check these provisions to ensure you maintain compliance.
- Certification transition dates: It's my understanding you would need your EC Certificate in hand on the application date to continue selling (i.e. be audited by a notified body before the application date so that you can fix any issues and possibly get your certificate before the application date). Getting caught in the scramble at the end and possibly losing some time on the market while you wait for your audits to be done/certificates to come in could be stressful.
Moral of the story: if you do want to go this route, you may want to plan it out so that your transition to the new IVDR is as seamless as possible. So, even if you can be self-certify now, it's probably a good idea to start building your IVDR-compliant systems and documents now so you can be ready to go.