Congrats on your upcoming bundle of barks, er, joy! 😆 Dachshunds are pretty smart pups so I don't think you'd have an issue when he gets older. There's a section in the training for putting "potty" on command that would be useful for this. https://www.braintraining4dogs.com/members/advanced-potty-training/potty-on-command/
That comes in useful if there's a designated area for him if you ever travel with him. When nature calls and he's in that field, it will happen even if potty isn't on command, lol. Having it on command makes it easier so they know it's what they're supposed to do in that area. I'm not sure if it's the breed or my husband's "training" but his Dachshunds were little devils about going inside so I highly recommend the command route and routine. Routine is one of the most powerful tools we have with helping dogs live in our world of rules. :)