I normally use the small/small also, but this is a oddball case, where the RD's wrap capacity might be exceeded. The chain length should then be set with the big/big plus 1 inch method. If the chain hangs loose in the two smallest cogs, that's OK because they should never be used. What that means is the RD's wrap capacity has been exceeded. When this happens, you should not shorten the chain to maintain tension in combinations that are not used.