The Gnomish Lexicon of the 1910s had G. nui “afterwards, then, later” and G. no “then, next, again; then, after(wards)” (GL/61), both probably based on the early root ᴱ√NO(WO) “after of time” which had the preposition ᴱQ. nō̆ “after (only of time)” as a derivative (QL/66). The word G. no was used as a preposition/conjunction in the untranslated phrase G. inig bast no odog saith (GL/51), perhaps meaning “*little bread then great hunger”.

Neo-Sindarin: In Tolkien’s later writings, Q. nó often means “before (of time)”, so I would not use either of these Gnomish words to mean “after”. However, we have no good words for “before (of time)” in later Sindarin, so for purposes of Neo-Sindarin I would use ᴺS. nui for such a meaning, assuming a reversal in Tolkien’s later conception similar to its Quenya equivalent. Admittedly this is a stretch, but I haven't found any better alternatives.