A mountain took a million years and nobody calls it behind schedule.

Schedules are a human invention applied to processes that never agreed to them. Most things that end up large were built by accumulation at a rate that would look like nothing if you watched it, and no external clock was running the whole time. The pressure you feel about pace is coming from a comparison, not from the work itself.

When you catch yourself measuring progress against a date, check who set it and what would actually happen if it moved. Then return to the rate you can sustain. Slow and continuing beats fast and abandoned in almost every case that matters.