The short answer is that it couldn't without sacrificing some other aspect of its Day 1 warplan. I usually point folks to this analysis whenever this question is asked here. It's fairly easy to understand and for the most part is accurate. There's some elements of Shattered Sword that should be included in discussions of the 1942 option, but its breakdown of the 1941 invasion question is pretty good.

In short, the Japanese merchant marine was already stretched beyond capacity on the first day of the war. It needed to support the invasion of Malaya, the invasion of the Philippines, civilian need (even in wartime, it's a bad idea to starve your home front) and the logistical needs of Japanese forces across the Pacific.

There was also the general unwillingness of the Army to participate in activities with the Navy in the Pacific. By and large, the IJA was focused on China and land operations in Southeast Asia including Malaya and Burma. Until 1942, the Army showed little interest in the war to the east of Japan.