I would say hold it in for a minute or so but don’t fight your body, if you body wants to expel it before then, do so.
In terms of tearing, it is technically possible, but very unlikely. If you insert it slowly, you’ll feel if you are touching the walls well before you do any damage. Also, you don’t want to be inserting it in too far anyway, you don’t have to insert the whole length of the tube, just an inch or so will do.