How far in advance should I make a reservation?

If you are planning on taking a large group there, then call ahead. Otherwise, you won't need a reservation for any of the Las Vegas buffets. I have never heard of one offering that option, other than for group seatings (8-10 or more people). Keep in mind that some of the buffets can have long lines, especially at peak times, so you are best to go in early (5 pm) or late (after 7:30 pm). If it is just yourself and/or your family, reservations will not be requried.

While popular, the buffet line for the Spice Market buffet usually won't be over an hour long. Less if you avoid peak times. If you have premium status with Planet Hollywood, such as second level or higher players card, you can usually use the VIP line, which is almost always shorter.

However, you might want to check to see if they have an all day meal deal. This is an all day pass and may allow you front of line privileges. You would just walk up to the VIP line or the hostess and they will probably seat you without you having to wait in the main line.

f you are really worried about it, I would go check the buffet out after checking into the hotel. At that time you can ask about reservations. More than a day should be sufficient.

I worked at a buffet restaurant and took reservations. It's fine to make really early reservations. You never know if they will be sold out a few nights in advance, even at a buffet in Vegas. Just cancel later if you change your mind. Also, you might want to re-confirm your reservation about a week before just because lots of people who book really early either no show or cancel, just because plans change. If you book reservations earlier in advance, sometimes, at least at my restaurant, you might get a nicer table. It all depends on the restaurant.