How long before baby tomato plants produce fruit?

You can always find out by looking on the packet or on the web for the type of tomato and its DTM. That is days til maturity. This is the number of days that average for that particular plant to produce fruit. Some are as early as 55 days (Early girl) to 90 days or more. Tomatoes can be classified as early season, mid season, or late season. DTM is measured from the time the seedling is set out, not when the seed in planted.