Remove the old filters and disinfect the system according to the manufacturers recommendation or the method I have posted many times and a search will bring up. Next with the line from the carbon block up to the RO membrane disconnected, install only a new sediment filter and flush the system for a couple minutes to remove any glues or binders left over from the manufacturing process. Next install a new carbon block and flush the two filters again for several minutes to remove any carbon dust or fines so it does not foul the membrane. Hook back up to the existing RO membrane if it has remained wet during the non use or replace it if it has dried out as it is shot, and make 3-5 gallons of RO only water without a DI installed or at least disconnected. Using your handheld TDS meter monitor the TDS of the RO water to ensure the membrane is somewhere around 98% rejection or removal. Finally install a new DI cartridge or properly packed refill and do a final flush for about 1 gallon to rinse the resin up and you are ready to go again.
At a minimum you will need sediment, carbon block and DI. If the membrane was dry it will need replacement also.
RO or RO/DI systems should be used at least every 10-14 days to keep them fresh, if it will be longer the RO membrane and the DI cartridge should be removed from the canisters, placed in zip loc or seal a meal bags with a little RO/DI water in them and stored in the refrigerator.