''Q. Here it is written: “It is very unwise for anyone to claim prematurely to have possession of the supermind or even to have a taste of it.” [Sri Aurobindo, Bases of Yoga] What is a foretaste of the supermind? ''
It is still more unwise to imagine that one has it. That's it.
... Before reaching the extreme limit of the mind, there are so many regions and mental activities which are not at all accessible to most human beings. And even for those who can reach them, they are not regions where they constantly live. They must make an effort of concentration to get there and they don't always arrive. There are regions which Sri Aurobindo has described which only very rare individuals can reach, and still he speaks of them as mental regions. He does not use the word supramental. <ref>https://incarnateword.in/cwm/06/24-november-1954#p27-p37</ref>