If a motor is running pretty well and you're upgrading one component, it makes sense to check out everything else before making the change.
But if a motor is barely running and everything is suspect, it's easier to dial in the electrics first. Most of that can be dialed in pretty well even if the engine is still running poorly.
The religious texts on carb tuning state clearly in their preambles (the part before they start ambling) that thou shalt setteth the spark and see the spark that it is good.
I should caution you, though, that everything I know about religion I got from YouTube videos.