I don't see a reason why they should wait I have looked over the instructions regarding this I was able to pull this information. 

"Use Schedule K-1 to report a beneficiary's share of the estate’s or trust’s income, credits, deductions, etc. on your Form 1040 or 1040-SR. Keep it for your records. Don’t file it with your tax return, unless backup withholding was reported in box 13, code B."

https://www.irs.gov/instructions/i1041sk1

Hopefully this helps!!