Most airlines usually do the initial training etc over winter with the view to be ready to roll for the following summer. However, IATA et al aren't predicting much of a return to pre COVID times for a few years. Then again, who knows? If they're talking about Atlantic traffic, they could well be right. It just "depends". The biggest hassle for airlines in Europe is the short notice requirements to quarantine etc. The segment of aviation that is booming right now is private aviation. We're absolutely flat out.
So - personally, I wouldn't be planning on finishing any training before 2023. Instrument ratings are expensive to keep current.