I would say that if you are trying to push and poke your white into place, then you are working at the wrong ratio and/or with too small an amount of product.
If you are working at the correct ratio and with the right amount of product for the nail, your product will follow what you and your brush want it to do and you will be simply guiding it into place.
You control the product......it's not controlling you!
I hope this makes sense!