I have this large world in pre-hardmode. I was searching for a method to kill the Wall Of Flesh and having as little problems as possible with Hallow and Corruption. I know that if you spawn the WOF, it will head towards the center. So, assuming I can kill the WOF quickly enough, it could die at the very edge of the map and release fully only one biome; this will help containing the spread and I could always recreate them later in a controlled space. If I can do it, I'll try to kill it on the right edge, so that my jungle is safe and I have the dungeon to stop part of the spread. Has anyone tried this? Do you think it would work? Any advice?
No matter where you kill the Wall of Flesh the X or V of crimson/corruption/hallow that is created as a result will always be created starting from the horizontal centre of the underworld. This means that your idea of killing it at one of the edges of the world won't have any impact on where the biomes get created.
Your best bet is to create new hellevators on either side of the new biomes that are at least 4 blocks wide (I usually go for 6) to help contain the spread of those biomes. From a practical point of view you can never fully contain them because new areas of crimson/corruption/hallow can be created every time you break a demon altar.
I haven't tried that but If is biome control you are concerned with that should not be your priority. The main X or V crimson/corruption and hallow are often easy to isolate with hellevators (and grey bricks). Instead, it is the small pockets that result from breaking the Altars that often spread out of control and by the time you noticed them they are very wide and troublesome to isolate. Assuming your method works, it will prevent a large chunk of jungle from getting corrupted immediately upon entering hardmode. I do think it is worth a try. Also you can always summon the WOF from the other direction and do damage until it is almost dead, and then wait for it to reach the side of the world before killing it. This would be much easier, though more time consuming, than trying to kill it upon spawning.
When it comes to farming in each biome, I always suggest taking the time to build arenas in each biome that are isolated to ensure there is always a place to farm. In a long lasting map it is almost impossible to prevent crimson/corruption from spreading. The only time I managed to completely isolate all corruption and hallow to control it, it took me a whole week of doing nothing but digging and purifying (quite a bit little longer than the hellevator method as I wanted to preserve certain biomes' natural formation).
After reading JonK's answer I doubled check and confirmed that the crimson/corruption and hallow indeed starts from the center, so I guess there is no alternative to preserve the jungle other than purifying it after entering hardmode then isolating it.