Adverbs are never placed just after a subject. When it would be the case, you need to move it either just after the auxiliary if there's one, or after the verb.
Another mistake you made is the conjugation of the verbs.
All of the above are acceptable. The second and third sentences mean that I am a person who goes to France from time to time.
So whenever I go to France it is customary for me to speak French.
In the first sentence I am telling you about a forthcoming visit to France.
You know that I speak English. I am telling you when I go there I will not speak English; it will be French.
Another example
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Tomorrow I will go to the gym.
1. When I go there (after lunch), I train using the treadmill.
2. In other words, when I go to the gym, I train using the treadmill. So it is customary for me to train using the treadmill.
3.When I go to the gym, I will train using the bicycle.
So I change my regular training scheme and train using the bicycle.
I would like to know those difference in French vantage point.
This is all true, but it doesn't generally apply to French. In clauses such as:
"When I arrive..."
"As soon as he gets here..."
"Once you've finished your food..."
French and English generally differ in their tense use. French generally uses the future tense (or future-perfect as appropriate), whereas English uses the present (or present perfect as appropriate).
So that's essentially why in Frank's examples, you see the pattern of fiuture + future in French, whereas in English you see present + future.