You can be added to the transplant waiting list, once you complete an evaluation at a transplant center and are found to be a good candidate for transplant. Once you are added to the national organ transplant waiting list, you may receive an organ fairly quickly or you may wait many years. In general, the average time frame for waiting can be 3-5 years at most centers and even longer in some geographical regions of the country. You should ask your transplant center to get a better understanding of the wait times.
The United Network for Organ Sharing (UNOS) manages the list of all the people across the US waiting for an organ transplant. UNOS ensures that deceased donor organs are distributed fairly using a transparent system. For kidneys, this is a combination of blood-type and antibody matching, time with kidney failure, and a few other factors that give people priority on the list (including being a child or being a past live kidney donor).
It is best to explore transplant as early as you can, and if possible before you need to start dialysis. This way, you might be able to get a transplant pre-emptively if possible. It can take time to find the right transplant center, complete the transplant evaluation, explore live kidney donor options, and get on the deceased donor transplant list if needed. If you are not yet on dialysis and have a GFR of 20 or less, you can already begin building "wait time" on the deceased donor transplant list.
UNOS will not confirm your placement or your status on the waitlist, but your transplant center must inform you when you are placed on the waitlist, and you should be able to confirm with them that you are active on the list. Your transplant team will call you and will need you to respond quickly if there is an organ available for you. Each transplant center has different procedures. You should discuss this with your team so you have a plan in place for when a kidney is available to you.