Qantas Silver to Gold: when can you start to use the lounges?

Apologies in advance if this is a rather basic query. I have attained the status credits to transition form silver to gold but have one more QF flight to meet the four flight requirement (my FF anniversary is in August). It's my understanding that after my next QF flight I'll officially attain gold FF status.

I'm looking at flying to Vancouver in a few weeks from Perth, if I make the booking today, will I be eligible to use lounges in Sydney and LA en route to Vancouver, or will I only be able to do so in bookings made after the date of officially attaining gold status?

I think it may tick over straight away so try Sydney and also explain at the gate. More likely LA though.

In my experience, QF system usually logs domestic flights straight away. So yes, by the time you get to Sydney you should be 'gold'.

Much appreciated!