If you are following someone for only 3 years that may be too short to see a difference in HIV progression between starting therapy at 250 cd4s vs starting at 400 cd4s. But, there are so many difficulties once you start therapy. The side effects, toxicities, difficulties in adherence, etc. are the reasons considered for deferring therapy. The Federal Treatment Guidelines for Adults recently changed. I'm not a fan of the Guidelines.
Every patient has an individual situation, which is different from everyone else.
Each individual has their own personal concerns, which will differ from other's concerns. Below is a discussion of many of the things to consider. But there are potential benefits to beginning therapy early, when CD4s are over 350 or at 500. The risks and benefits should be carefully weighed by the patient, with their doctor before deciding when to begin therapy. HIV-related CNS disorders may be more likely to occur as viral load gets higher.