My determinate tomato plant now has 25 or thirty small tomatoes set on and is still blooming profusely. The indeterminate plant has one tomato set on. It is also beginning to bloom plentifully and I have no reason to believe it will not also be a big producer. The two plants are simply following different schedules.
Each plant had one outlier fruit develop much earlier than the others. My hypothesis is that the plant produces this outlier in order to test that conditions are favorable and then sends a hormonal feedback to the plant, stimulating it to increase blooming. It seems like the logical explanation.
I have never read that this is true but I bet it is. See if your plants don't produce a very early outlier and let me know.