The time to have a facelift is determined more by "anatomical" age than "chronological" age. Simply put, if you took 3 female patients that were all 48 years old, all of whom were physically fit, nonsmokers and who took good care of themselves you very well may find different "surgical" ages for each of them.
Patient A might have loose skin, heavy jowls and a turkey neck. She would certainly be a good candidate for a facelift and neck lift or a facelift by itself depending on her anatomy.
Patient B might have mild jowls and a little fat under her chin and would therefore be better suited for a Mini Facelift or modified facelift with liposuction under her chin.
Patient C might look like she is 28 and not have any noticeable jowls or loose skin and may need only some botox injections or a chemical peel.
So end of the day, the best way of answering this question is to sit down with 2 to 3 experienced and established surgeons and let them examine your anatomy, hear what your goals are and let him / her give you their best advice.
The benefits of early surgery are:
1. Less invasive procedure will be needed
2. Quicker recovery time
3. Less costs associated with surgery
4. More natural and less drastic changes to your appearance
5. Preventative in the sense that the jowls and turkey neck will not be as bad down the line (you will still keep aging however and will need additional surgery down the line)
The key again though is to let a well qualified surgeon help you understand and reach a decision that makes sense given the anatomy that you have.
Increasingly patients are seeking out facelift surgery at a younger age than they did 30, 20 and even 10 years ago. This has happened due to many factors including the increasing popularity of Mini Facelifts that feature natural / subtle results with quick recovery and the desire for patients to avoid more excessive surgery at a later time in their lives. This "natural" approach has worked well for many patients. It is quite possible that 10 years ago most surgeons would have told you to wait another 10 years and have a full facelift, now it is more likely that you will be offered a modified version of a full facelift or a Mini Facelift by most surgeons.
Also make sure to have your neck examined by the surgeons. It will be important to determine what if anything needs to be done there.
You are on the right track by asking good questions,