If you can pay your balance due within 120 days, the IRS says to do not sign up for an installment plan.
You can file now and pay as much as you can now.
Another
short term option is to file an extension. This delays your filing up
to 6 months until 10/15 or anytime between now and then.
Your tax
is still due on 4/15, but the failure-pay-penalty is not that severe.
If you think it will take longer than 6 months, I would say do an installment agreement. Here's some instructions:
https://ttlc.intuit.com/replies/3301261
https://ttlc.intuit.com/replies/4062611