Difference between Once and When

ONCE vs WHEN: NOUN

For one time; by limitation to the number one; not twice nor any number of times more than one.
At some one period of time; -- used indefinitely.
At any one time; -- often nearly equivalent to ever, if ever, or whenever.
At one and the same time; simultaneously; in one body.
Once and once more; repeatedly.
One and only one time.
Multiplied by one: indicating that a number is multiplied by one
By one degree of relationship.
At any time; ever.
At one time in the past; formerly.
One time only.
As soon as
At a previous time
On one occasion
Formerly; during some period in the past.

As soon as
At what time.
Used to introduce indirect questions about time.
Used to introduce questions about time.
At the time that; when.
Which time; then; -- used elliptically as a noun.
While; whereas; although; -- used in the manner of a conjunction to introduce a dependent adverbial sentence or clause, having a causal, conditional, or adversative relation to the principal proposition.
At what time; at, during, or after the time that; at or just after, the moment that; -- used relatively.
At what time; -- used interrogatively.

That's enough, a command to stop adding something, especially an ingredient of food or drink.

When at any time; whenever; as soon as.
Immediately; forthwith; without delay.
Once for all.
Without delay; immediately: often merely expletive: as, John, come here once.
At some future time; some time or other.
One and the same time: usually with at: as, they all cried out at once. See phrases below.
One time.
At any time; in any contingency; on any occasion; under any circumstances; ever.
(idiom) (once more/again) As usual; in typical fashion.
(idiom) (once more/again) Another time; again.
(idiom) (at once) Immediately; instantly.
(idiom) (at once) All at one time; simultaneously.

At what time? at which time?
At the or any time that; at or just after the moment that; as soon as.
At which time.
At the same time that; whereas; while on the contrary: used adversatively, to denote contrast or incompatibility.
When is often used as a quasi-pronoun, meaning ‘which time,’ introducing a dependent clause after since, till, or similar connective denoting time.

Finally, Then, Never, Again, In one case, At one time, One time, Quondam, Former, Formerly, Erstwhile, Onetime, Sometime, Past, When

Eventually, Twice, Then, Never, Again, At one time, One time, Quondam, Former, Formerly, Erstwhile, Onetime, Sometime, Past, When

In grief, the two are connected once more.
Also, if the outcome is the same whether a transaction is performed once or more than once, thenrecovery from catastrophic failure can be simplified.
Once you reacquire your Philippine citizenship, you will once again enjoy full civil, economic and political rights under existing Philippine laws.
It seems crazy that you have to pay twice: once for your primary application and once again for your secondary applications.
Since birth and heaven and earth, all three do meet In thee at once, which thou at once wouldst lose?
We do NOT want to validate more than once, or submit more than once.
Once a move is made, staff maintain contact with the client once a month for three months, and then annually thereafter.
This means that any employer processes involved must be run more than once a year and potentially once for each specific employee due date.
Once the constitution is amended once, such a coalition is identified and subsequent amendments are easier to promulgate.
She says he kissed her once in his bedroom and once by the pool at a local country club.

When love blossoms between Kena and Ziki, the two girls agonize when they must choose between happiness and safety.
We use Singleton pattern for this and instantiate the logger when the first request hits or when the server is started.
This can be done when the auditors meet Global Fund requirements and when the Principal Recipient is willing to share its audit report.
They can be used when a block only needs aligned with other blocks on that same level of indentation, or when alignment is trivial.
Having a record of what was texted, when and by whom can be essential when it comes to solving customer service disputes.
When to Promote, and When to Avoid, a Population Perspective.
When considering whether or not you need a new air conditioner, think about when your current one was installed.
Matters get particularly complex when there are children involved or when dealing with a combative spouse.
Therefore they need support and training when developing bid document specifications or when evaluating proposals.
Reminds me of the days when Ebay when they started competing with Amazon.