Install the first three rings into the stuffing box and then use the gland to make sure they are seated correctly. Then, install the fourth, start the pump and adjust the packing. If you can then get in the last ring, install it - but make sure there is a drip or that the packing is running at a temperature where you can leave your hand on it. The warmer the bearings run, the hotter the packing will be and vice versa. The heat travels down the shaft.
Cut a 1/4 inch piece from a new ring of packing before installing and flatten it a bit. If you don't, you will never get it in the stuffing box. Many people will try to force it in and put too much pressure on the shaft and packing. Most of the new packing is graphite impregnated Teflon but it is still Teflon and will wear right into a shaft and groove it if you are not careful.
When your bearings stop climbing in temperature during the first start-up or repacking (probably hitting over 160°F), make sure the temperature starts to come down again. If it does not start declining, stop the pump if you can and let it cool down to ambient temperature - at least an hour - and the temperature will usually max out 10-15 degrees cooler. At that point, it should continue to drop until it is running at its normal temperature.