Yes you can. You will need to sort out accounts though plus tax references and make sure you file annual returns.
Any reason to do it now? Can incorporate a basic company in days and you get time to sort tax ref etc. So why not do it when you are ready.
It sounds like you haven’t done this before so I would strongly suggest getting a QUALIFIED accountant (ACCA, FCA , ACA , FCA) to help you and make sure this structure is appropriate for your circumstances from a tax and commercial perspective. They will charge but you will probably save that several times over in the longer term.