imo the time for offensive was never. The offensive should happen “naturally”. If they had enough resources, they would be slowly pushing Russia back just like they are being pushed back currently. The whole “spring offensive” was just as dumb as Russian plan to conquer Kiev in 5 days or whatever insanity they had in mind.
That comes down to the “they are being out-everything” from your earlier comment. Europe needs to start spending much more money on the war, but that wouldn’t be popular amongst the Europeans and therefore won’t happen, sadly.