FLR - when to apply with postal application

[chibakun]

My wife's visa card says that it's valid until the 28th June 2015. We need to apply for another 2.5 yr FLR for her spouse visa and we are going to do this by post. Given that you don't know how long it's going to take for them to return the processed documents and grant the visa, when should we apply?
Do they need to have the application by that date or to have processed it?

[vinny]

Your wife should post the valid application shortly before your leave expires, preferably no sooner than 28 days before it expires. It doesn't matter how long they take to process her application, as your wife's leave is "treated as continuing" while it is being processed.

[chibakun]

Thanks