Typically you will need to post a dog through teething, sometimes longer (maybe even months longer) depending on the individual dog.
It is much better to learn to post them yourself—that way you can deal with the little emergencies that may crop up (things like posts that have gotten wet or dirty, the post popping out of the bottom of the ear, a possible infection starting to show up) right away instead of having to wait for an appointment. A posting should be changed every 3-5 days—it can be tough to get to the vet that often. A lot of vets don't do that good a job of posting anyway—they have other areas that they need to focus on knowing how to do right; posting ears is way down the list.
It's not really that hard—you WILL feel all thumbs at first and likely get a little frustrated, but pretty soon, you'll practically be able to post ears in your sleep.
We have some tutorials that show the method that most of us use; take a look at these:
Ear cropping and aftercare, do's and don'ts https://www.dobermantalk.com/ear-cro...-s-don-ts.html
How To: Post Using Backer Rod https://www.dobermantalk.com/ear-cro...acker-rod.html
How To: Gently Remove Ear Posts https://www.dobermantalk.com/ear-cro...ear-posts.html
You can also browse though the ear cropping sub forum here: https://www.dobermantalk.com/ear-cropping-posting/
I gather you're working on figuring out how to post yourself? Feel free to ask questions here or even come on and moan about your problems. If you post a picture of your posting job, we might be able to give you a few tips about what you might need to do (praise and support is nice too
) Just about everyone here has had to learn how to post for the first time—believe me—we've all been there.
By the way, just an extra comment (I don't know what stage you are at in this process)—you can't post ears until the crop is COMPLETELY healed—if you see any scabs or open areas, it's too soon. Typically it is about a week after the stitches are removed before you can start posting.
If you tell us about where you live, we might be able to refer you to someone who can guide you through the steps in person—seeing something done once and doing it yourself under hands-on guidance is so much easier than learning through online pictures, no matter how good they are.