All seeds produced by a single plant will be the same genetically except in rare circumstances such as a sport.
That being the case you can save seeds from any tomato in the plant. For myself, I choose early fruit due to the bees not being active in my garden when early fruit are set reducing the chance of an accidental cross.
It’s a good idea to save seed from more than one fruit just in case though
KarenO
Be sure your plant and fruit matches the attributes of the variety by researching and save seed from your best healthy plants only. Some serious diseases can be carried on and in tomato seed. Ferment and dry well before storing.
KarenO
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