Your proposal works, but I see the expression used in a simpler fashion.
one time only
only one time
only once
once only
once and never again
today only (a one-time event)
the first and the last time
I'm
only going to explain/do this
once.
Update:
Here is one more translation from our idioms section.
Looking around the internet, I see that some have suggested a couple of refrains, like 'once bitten, twice shy' and 'fool me once, shame on you; fool me twice, shame on me'. These both mean 'once is enough', as in, you don't want to experience something twice (especially said of a painful/hurtful event).