One other consideration. Is there any source of re-infestation of trash fish? For example, a neighbors pond above yours that drains into your pond during high rainfall events?
If there is a chance BH can get back into the pond after all the fish are destroyed, it is important to get the desired fish established as quick as possible. Give them the upper hand. If it is a year before re-stocking, and in the mean time some more BH come into the pond before the correct fish get established, the problem can start all over.
