If you aren't going to get reimbursed for the PCS move until 2018, I would not recommend claiming your moving expenses on your 2017 return. Your PCS reimbursement will show up on your 2018 DFAS Form W-2 as taxable income (Box 1 and Box 12, Code P) and you will need to claim the moving expenses the, in 2018, to avoid getting taxed on the reimbursement.
If your claimed moving expenses exceed the amount reimbursed by the military, you will get an additional moving expense deduction for the difference. Yes, you can split up the claim to get that deduction in 2017 but it can be a little tricky and confusing.
The following post explains this in more detail when the claim is made in the same year as the reimbursement: PCS move