Only 1% Of Americans Know This Gomerry Secret. Do You?

I can only do so much in this time. Or i can do only so much in this time. When only after, only if, only in this way etc.

Only after lunch can you play. In only when , there is a sense of urgency, a slightly more 'involved' writing. It was only when is by comparision more 'relaxed' writing, more like someone is recounting something to someone. The question asks for a general answer but gives only one special context. In general, only and but only are not substitutable. *they but only work that way occasionally.