Please do not change the order of episodes between the season 17 finale and the season 18 premiere. The current template is built to only allow one set of previous/next episodes. The set we use is the order based on the index number, not the actual airdates.
However, soon there will be an upgrade to the infobox that will allow both orders to be displayed. Such a navigation technique is already being used on other wikis, such as Memory Alpha and Tardis Data Core.