Just like John to twist words...
What you do depends on the construction method you use. Should you be using a modified thinset, large tile, over a waterproofing membrane (I don't care whose you are using, even if it is allowed), you should wait awhile to allow the modifiers to dry out. But, done over say a mudbed or cbu where there is a path for moisture to escape, or on a wall where you can't be walking on it, allow at least the minimum time and do NOT place large loads on things until things are more stable. But, should you be using an unmodified or rapid setting thinset, in most cases you can grout after 24-hours with little risk. Avoid rolling heavy equipment, ladders, vehicles, furniture, that can create large point loads, etc. over things until the stuff has a better chance to set up.
Should you choose to use modified thinset over something like Ditra, tests have shown that the thinset hasn't properly cured and dried at over two months...the instructions and methods are defined, and if you follow them, you should not have issues.
Does it hurt to wait longer? No, and with a DIY'er, that may be more the norm.