There are pros and cons to enrolling in Medicare. There is a 30 month period when Medicare would be secondary to an employer group health plan (called the "Medicare secondary payer period") from the first date the patient is eligible for Medicare. If you started dialysis and began a home training program before the end of your third month of dialysis, you'd be eligible for Medicare from the first month you had dialysis.
Assuming you have enough work credits, you will get Part A free if you want it. Part B has a premium. If you do not want to enroll in Part B because it has a premium, I'd suggest you not enroll in Part A either. That will allow you to enroll in Medicare Part A and B anytime you want or need to.
If you enroll in Part A and waive Part B, if you lose your employer plan down the road (or if your plan stops covering your providers), you'll only be able to enroll in Part B during the open enrollment period (January-March annually) and Part B won't take effect until the following July 1. This can mean a gap in coverage. Patients who do this need to enroll in Part B during the open enrollment period that will assure that they have Part B coverage when the Medicare secondary payer period ends and when their employer plan starts only paying secondary benefits.
If your employer health plan pays at least 100% of Medicare's allowed charge and if you have Part B, ANY provider that accepts Medicare assignment (get checks directly from Medicare) must write off any balances it would normally bill you. This could include deductibles, copays or coinsurance that could be more costly than the Medicare premium.
Contact your state insurance department to ask if you enroll in Part B now if you could later enroll in a Medigap plan if you need one. Federal law only protects Medigap rights to those 65 and older (including those with preexisting conditions) for the first 6 months they have Medicare, but some states have expanded protection to younger people and/or those who have or lose employer coverage.
Social Security representatives are supposed to advise those with employer group health plans about their options related to enrolling in Medicare. Here's the Social Security policy related to people with kidney failure (ESRD) and Medicare secondary payer: