Is there ever a good time to start training? Probably when others aren't. Sure, you could wait until the industry has recovered but then you'll be in the same position as everyone else. Or you could go for it now and spend a fortune keeping current only to be passed over because you qualified too long ago.
If someone has the money and the dream, then my advice would be to go for it 80%. By that I mean get a PPL, do some hour building, take the ATPL exams, get an IRR, CBIR and CPL - but do it all single engine.
Then stop.
You've just spent £30k to get within a month of the finish line, with all hoops jumped through. No need to worry about ATPLs expiring (for at least 7 years!) Nothing to keep current - just let everything lapse until you're ready for the last step - because you've only got 10 hours of MEP training and an MCC/JOC course left to do. When the time is right, you're a fATPL with a one month lead time. And when you write your CV the important bits (The MEIR and MCC/JOC) will be brand new.