As a typical impatient aquarist, I'm totally on board with everyone who hates waiting for stuff like pods and wood to be ready for aquarium use. There is, unfortunately, no real "shortcut" to preparing wood for use. It simply needs to become waterlogged in order to sink effectively.
My personal favorite wood is Manzanita, which we offer regularly here at Tannin. I love Manzanita because it makes creating a beautiful aquascape near effortless...I mean, you can literally drop a piece in your tank and looks like you're a master aquascaper! Okay, maybe it's not THAT easy, but it really has an amazing morphology, with many twisted and curving branches, great color, and beautiful texture..and you can often "interlock" a few pieces together to create really amazing hardscapes!
In my opinion, it's like the perfect aquascaping wood, as it lasts a very long time when submerged, and continues to look great throughout its ridiculously long "service lifespan". Just how long? I had a piece that was continuously submerged for 11 years, and other than a slight "patina" of algae, it looked as beautiful as the day I first placed it in my aquarium!
Manzanita is actually a sort of "catch all" term for species in the genus Arctostaphylos, an evergreen shrub or small tree that occurs in Western North America. They are commonly identified because their smooth orangish or reddish bark and very twisty branches. There are 105 species and subspecies of manzanita, so it's a pretty diverse group!
(a typical Manzanita bush in nature- pic used under CC-BY SA 3.0)
Through trial and error, I've found that most of the Manzanita wood we offer (which typically has a branch diameter of no more than about 2"), takes about 4-7 days to get good and waterlogged to the point where it won't suddenly float right to the top of your tank. Now granted, this is an estimate; a sweeping generalization I am offering, based on my own personal experiences. I've tried to rush it many times- in fact, I tried this quite recently- with predictable (buoyant!) results! You can't rush the process.
Every piece of wood is unique; each branch has characteristics that may render it more or less buoyant than another piece of similar size. Manzanita, however, seems to be fairly "predictable" when you're working with pieces of a certain size- like the ones we generally offer for sale, which are anywhere from 15 to 21inches long , and generally have a branch circumference no greater than about 2 inches.
You can certainly speed up the process a little bit (maybe by a day or two, in my experience) by boiling the branch prior to a soak, but in my humble opinion, it's hardly worth the trouble...and besides, how many of us have the cookware necessary to accommodate a 20" long branch on our stove?
The good news about the prolonged soak is that any tannins contained in the branch will start to leach out, so you won't have a huge burst of 'em in your tank when you place the wood. I've heard (and can sort of anecdotally confirm with my own experience) that Manzanita has far less tannins in it than many of the other woods we use in aquariums (like Mopani, "Bog Wood", etc.); nonetheless, be prepared for some release of tannins and the tint associated with them.
Obviously, we are not bothered by this tint, but not every aquarist feels the same, so you'd want to soak as long as you can handle it to get the wood to release as much initial tannins as possible before placing in your display! Even with a prolonged soak, of course, you may still see some tint in the water. The best way to reduce this is to utilize activated carbon or other chemical filtration to remove it.
If you're the impatient type, don't mind the tint associated with the initial soaking of this wood, or simply don't have the facilities to soak it, you may elect to place the wood in the display and let it waterlog there. Although not the best way to go, I have done this many times. The only caveat here is that you might want to give the wood a good rinse before submerging it, and you really would be advised not to do this while fishes are in the tank (for a number of reasons- most obvious being that the water chemistry might be affected rather quickly, and that's never good...).
You will, of course, need to weigh the wood down with something (rocks, sand, etc.) to hold it in place while it's soaking- otherwise, you've got a floating log in your tank! And you might find yourself making frequent water changes in the early stages if your wood releases significant amounts of tannins and other visual impurities.
So, the whole point of this treatise is that Manzanita is arguably one of the best woods for aquarium use, but it still possesses that maddening buoyancy characteristic that we all have come to despise so much...and there isn't a whole lot you can do about it, other than...be patient, and savor the anticipation of knowing that soon, you'll have a killer new centerpiece for your aquascape!
Stay Excited. Stay patient.
And Stay Wet.