Just as an FYI- the wood will release tannins, and those will turn your water the color of tea, but not that dark. This is NOT a bad thing, just just need to know that's what is happening when your tank water changes colors LOL. It will lower your Ph so make sure the fish you get will be happy in the Ph it supports.
And if it is fishless I would do at least a 50% water change to cut your ammonia in half. If it gets too high it will hinder your cycle. And 5ppm is getting near that point.