How strict is the timing of the trigger injection? What if I take it late?

The trigger injection causes the final maturation of the eggs and sets off the process that would normally lead to ovulation. Egg retrieval is planned for roughly 34–36 hours after the trigger, so that the eggs are mature but haven't yet been released from the follicles. That's why the time matters. Being a few minutes early or late is generally not a problem. Larger delays can matter more: if the trigger is taken much too early relative to retrieval, eggs may be released before collection; if much too late, eggs may be less mature. Your centre has chosen the time to match their procedure schedule. Practical tips: set two alarms, prepare the injection in advance as you were shown, check the exact dose and the name of the medicine against your prescription, and confirm how the medicine should be stored. Write down the exact time you took it. If you miss the time by more than a little, take the wrong dose, or something goes wrong with the injection, such as the medicine leaking out, contact your centre immediately rather than waiting until the morning. They may adjust the retrieval time. Always follow your own doctor's instructions on timing, as protocols differ.