There are 2048 possibilities for each word.
The first word can go into one of any 12 position in your wallet seed, therefore 2048*12. The next in any of 11, and the last one is 10.

so you will have total of 2048 * 12 * 2048 * 11 * 2048 * 10, or 2048^3 * 10 * 11* 12 which eq= 1.1338714e+13


a normal computer, with 500,000 attempts per second need less than 10 Years.

Thus, a normal computer may need a few years, but adding more physical devices may reduce that time for several months, and perhaps days. The matter depends on the economics of cost, which is calculating costs for the physical devices and the money that exists in that seed.

If you know any letter, a place for the word, the shape of the word or part of it, you will reduce the time, perhaps a few days on a regular computer, so try to remember anything because it will reduce the time a lot.