My daughter started using ASL about a year before she began learning English, but for the most part she's been acquiring both simultaneously. She was taught ASL and placed in an immersive ASL-focused learning environment, she picked up English organically outside of her structured classroom experience. She prefers ASL with ASL users and English with those using English. Since she's begun reading, her English vocabulary has leaped far beyond her ASL vocabulary, so in general I think she finds it easier to communicate using English nowadays. She says she likes both equally. Some problems writing English, but then, she's 6YO, so still learning 
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