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.

I can only do so much in this time. Or i can do only so much in this time. I am from bangalore and people here tend use the word only to emphasise something in a sentence. We are getting that only printed. What is the proper way to put it? The oxford english dictionary defines but only (which can also occur as only but) as meaning ‘ (a) only, merely; (b) except only’, and comments that its use is now poetical.

What is the proper way to put it? The oxford english dictionary defines but only (which can also occur as only but) as meaning ‘ (a) only, merely; (b) except only’, and comments that its use is now poetical.