It's always difficult to accurately predict time to LH command, but the short answer - there is no quick way of achieving it. Fleets like the A380 will never be short of command bidders.
If you join now you would have 4000ish pilots ahead of you and the top 1400 or so are senior enough for a LH command with current fleet sizes and planned expansion. In reality very few of that group will retire in any great numbers within the next 15 years or so. And once they have thrown in the towel you will still need to rise at least another 1000 places from your 4000+ starting seniority in joining. I reckon at least 20 years to Long Haul captain if you joined next week, but it really is a guess, Wiggy and others may have better perspective on this.
And bear in mind when the 2011 intake joined most reckoned on maybe 10 years to a LGW SH command and more like 15 for LHR - it turned out to be 4 years for both. But SH really is a different kettle of fish!