When is an application withdrawn

Hi,

My wife and I withdrew an application to re-apply at a later date when more documents fall in the 28-day period for a stronger application. We are aware that re-applying while the first application is 'active' may mean that it is treated as a variation, which would mean our documentation would be invalid as it would be dated after the first application. Home office guidance says that an application is considered withdrawn when the online form is received, however it is not clear at what point this is (when submit is clicked or when a case worker has read it and matched it to your application?).

At what time since giving in the form does the application count as withdrawn (and a subsequent application would not be considered a variation of the first one)?

Thanks in advance for any insights.