Starting from zero? Of course it's different for everyone, but I'll try to give you numbers based on an average person (if there is such a thing). And it also depends on how much you practice. So let's say the average practice time is an hour a day:

Campfire type songs or worship songs with basic open chords - 4 months

Slightly more advanced songs maybe with some bar chords - at least 6 months

intermediate to advanced rhythm - at least 1 year

intermediate lead playing - 6 months to 1 year

advanced lead playing, fast soloing, etc. - at least 2 years

sweep picking - at least 2 years


Now, let me add that these estimates could be WAY off. Some of them you might learn quicker, while others take you longer. Everyone is different. Personally, I've been learning things fairly quickly, but I spend about 3 hours every day, and I spend way more time on lead than rhythm. It's been 11 months since I've started, and I would say I can play any intermediate lead songs/solos and some advanced lead songs/solos. I can sweep pick at medium speed, and I have all my open, power, and bar chords down. But I could still use some work on my chord changes between certain chords.

So it all depends on your short-term and long-term goals and how much time you put into it every day. Whatever you're learning, try to make up an exercise out of it where you're switching back and forth between chords. Or just work on one chord by fingering it, then lifting up all your fingers, and then putting them back down in the right places simultaneously. That'll help you get each chord down.