In French, to express "by the time that...", you use "le temps que" + Mode subjonctif.
How to use "le temps que" with Mode subjonctif in French
Look at these sentences:
Le temps que nous arrivions, mon avion était déjà parti !By the time we arrived, my plane was already gone!
Le temps que je finisse de manger, il avait déjà bu une bouteille entière.By the time I finished eating, he had already drunk a whole bottle.
To express an action that takes place by the time / in the time another action happens/happened, you will use :
le temps que + verb in Le Subjonctif
ATTENTION:
Don't get mixed up with sentences like "le temps qu'il fait" (lit. the weather [that] it does) or "le temps que ça prend" meaning the time (that it takes).
Here the verb is in L'Indicatif, NOT Le Subjonctif, and it does not mean "by the time...":
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