I did the math. A standard cremation takes 2-3 hours at a temperature of 1400° Fahrenheit. This would require at least 12lbs of charcoal briquettes. Charcoal is made using a 3:1 ratio with wood (36lbs of wood) and a standard lolblolly pine harvests 470lbs of usable wood. (48 per day.) There were 6 million jews killed in the Holocaust across 4 years (1941-1945) averaging 1.5 million a year across 6 camps. Given the number of hours in a day, the time to heat and cool and other factors such as breaks, each oven reasonably cremated a max of 4 bodies per day.
That means each camp had approximately 1,028 ovens averaging 171.3 ovens per camp burning a total 49,344lbs of charcoal per day per camp, equaling 18,010,560 per year, and 72,042,240 across the entire four years totaling 432,253,440lbs for all camps. This is would have been created from the equivalent of 1,296,760,320lbs of wood harvested from approximately 2,759,064.6 trees. A little over 500,000 more trees than compromise the entirety of the Atlantic forest in Brazil (2.2 million) a mass of wood that's the exact size of Mexico. For reference I've attached a picture of Mexico overlaid atop Europe. This forest would stretch from Ireland to Turkey and from France to Poland. Such a forest has almost certainly never existed on the European continent except for during the first settlement of humans onto it's soil.
A standard forest harvesting for milling purposes can harvest 100,000 feet of wood per every 10 days, equaling about 10,000 feet of wood per day. A standard lolblolly pine is 60-90 feet in length, which averages out to about 75 feet of wood per tree. To harvest 206,929,845 feet of wood at 10,000 feet per day it would take 56.69310821917808 years to harvest (56 years and 52 days.)
You would then need to mill the wood afterwords to be useful as lumber. 9 fet of lumber can be standardly milled in about 5 minutes. 206,929,845 feet of lumber being milled by a team of men in 16 hour shifts with no days off would take approximately 119,751.0677083333 days or 328.0851170091324 years (328 years and 29.2 days.)
You would then need to turn this lumber into charcoal briquettes. A standard briquette drum is composed of two 50 gallon tanks welded together. This can hold approximately 15.94333333333333 feet of cut lumber at a time and takes 3 hours to burn with a 24 hour cool-down time afterwords. To be conservative with this estimate we can say that the S.S. used approximately 12,979,082.89776291 100 gallon briquette barrels (rounded up to 12,979,083 barrels) and burned all of the wood in a single day with an additional 24 hour cool down period before transporting it to the camps for use.
In order for the briquettes to have been ready for use on the opening day of the concentration camps on 03/22/1933 the S.S. would have need to begin harvesting the wood on 12/29/1548 384 years and 83.2 days before the opening of the camps on 03/22/1933, immediately following the end of the Schmalkaldic War with the Holy Roman Empire.
Even removing the ovens from the equation you would need just as much, if not more wood when factoring in the surface area and loss of heat due to the open air environment and that's without even getting into the storage and transportation of the wood or how it would be continuously fed into the pit.