Varies all over the map - depends on manufacturer, vehicle model, trim level, options, popularity, parts availability, shipping, etc., etc.. Ask the dealership of the vehicle in question.
If you're looking at Cadillac then Matt, at our Vendor Lockhart Cadillac, will give you a straight answer. Most CF members can reply on personal experience or current hearsay.
Some newer U.S. makes/models have 6 to 11 month wait times. I "built" a few cars back in the 60s and even those wait times were 7 to 12 weeks.
All the parts, powertrain, suspension, colors, options, upgrades have to be programmed to arrive at their exact spot in the plant and on the assembly line at precisely the correct time
for that car for installation. It's nowhere near "mix & match".