1. were deferrals withheld? but not sent in? in that case you have late deposits. See VFCP, and Form 5330, and look up late deposits to retirement plans
2. were deferrals not withheld? but they should have been? In that case you have a missed opportunity to defer. See EPCRS, if there were deferral elections, or no deferral elections, or match or no match, the actual amount will vary, but it all covered in the IRS's EPCRS rev pro.
Note: the custodian not being ready isn't a valid excuse. Plans encounter this all the time, and purposely pick a special deferral start date farther out, that is written into the plan document, for this very reason. The give service providers time to get set-up with all the info from the sponsor. Even in the event of an unexpected delay, there is no reason why the deferrals couldn't have started on time, and the plan open up a temporary account, such as brokerage/checking/savings account etc in the name of the plan into which to deposit the deferrals. Then they would be deposited to the trust on time, and then once the regular custodian is ready, the money can be transferred to there.