Although they might attack Raqqa in as little as a week, conditions could change, or deals could be make.
Last Summer, everything was being set up to liberate Mosul, but the Shia militias, Iranians and Iraqi Army under-performed in Tikrit; and the Iranians shifted their priorities to Yemen and Syria.
The Kurds are solid infantry, but it would not be their territory they are fighting for. So if the other players in the operation lose commitment, they are unlikely to bite of Raqqa on their own.
It seems that Iranian and Iraqi fighters are awful.
fought to a draw for 10 years with a million dead and we took Iraq in 6 weeks.
Interesting.
That is the first step.
But the big battle that send ISIS scattered will be in Mosul.
They are WAY dug in there.