I think you only get a few times to take it away without serious issue....when they are itty bitties and are not using it as security, and then when they are a little older and you are able to communicate why it is gone.
We waited until the oldest was 21 months, and she was verbal. We waited until the youngest (just turned 2 on Sunday) was 23 months old, and was verbal.
You've done the first step I'd give advice to.....only at bedtime, and not finding it for them in the middle of the night (oh, so hard!).
With the first kiddo we talked about giving it to other babies who needed it. With the second, we lost it on a trip back from GM's, and could not find it that night at all. I took it as divine intervention. (I found it the next morning in my oldest's pillow case, and then hid it.)
Both kiddos struggled the first night, but it really didn't take long. And, if you have already resigned to the fact that you won't get up in the middle of the night to get it, then you can handle a few nights of the same fussing at the beginning of the night wanting it.
When either asked, we just reminded them it was "all gone, and another baby needed it."
I'd wait a few months, unless you think your little one will be able to understand that it is "all gone." Good luck, mama. Good job, so far!!!