Telling a parent that their child might need an early intervention evaluation is arguably the hardest conversation a center director will ever navigate. You are dealing directly with their absolute biggest fears for their child's future.
The most important rule is to never use diagnostic terms. You are an early childhood educator, not a developmental pediatrician. Do not tell a parent you think their child is on the autism spectrum. Instead, bring highly specific, documented observations to the meeting. Say, "We have noticed over the last month that he is struggling to transition between activities compared to his peers," and physically show them the objective daily logs. Frame the conversation entirely around getting the child the additional support they deserve. When parents understand that you are advocating for their child rather than labeling them, they are far more likely to engage constructively with the referral process.