Re: How long until the new referendum will be called?
Unfortunately, there is no point to call it now.
The root cause is not BrExit related. The people discussing the second referendum (most of which are middle class) FAIL to understand populism. The way populism works is by delivering its agenda as a stream of shit punctuated by specifically selected pieces of truth in key locations. Joe Average Citizen sees the pieces of truth and happily consumes the stream in between.
That would not be an issue if the opposing narrative was run from a truth perspective. The problem is that it is not. Plain and simple. At some point during Tony Bliar's rule we swapped places with Brezhnev and Suslov and the centrist narrative which also happened to be the government one ended up as an endless stream of lies(*). These are supported via an orchestrated social media campaigns and "influencers" on government payroll (same as it used to be in USSR).
Changing it to truth at present is not going to work either as people are conditioned that it is a stream of lies and treat it as "expert opinions", "f*ck business", etc.
It will take a combination of a very rude awakening with nothing in the shops and no salary/benefit checks combined with the powers that be actually SWITCHING the narrative back from Brezhnev/Suslov mode to a truth based one for things to change. Prior to that it is pointless to do it and let's hope we survive to the point where it can be done.
(*)I already went through the Crimea "Blockade" as one example of such "lies at scale" narrative. It's not the only one. Pretty much anything significant in the last 2 years foreign-policy wise has proven to be in the same category - where the prime minister dons asbestos knickers and proudly quacks while bottom is trying to conflagrate.