I wouldn't want to leave it too late and not be able to progress to the next stage in CTC for example, if the bank were still setting up the loan. On the flipside, if I applied too early, it would unnecessarily bring my 'payment holiday' forward...
Definitely have everything set up before you start, don't want to risk not having the funds to keep the bond payments going. BBVA will take about 3 months or so, they're pathetically slow I've been told...
No the repayment holiday starts from when you use money from BBVA loan to pay CTC. For example, if you had around £30k savings, you'd use that first to pay for basic training (£20k) and the first few bond payments (first one is due at the start of flight training), then when you've used all your savings you'd then draw money from BBVA to continue paying CTC. It's at this point that the repayment holiday starts.