Let's just assume for the sake of argument that the school district's policy is that only children of two non-native speakers, who have been in the country for fewer than three years, can apply for the linguistic exemption, since I believe that in the near future that's what they'll be implementing, anyway, due to the fact that they are working extremely hard to make this a program for children who have special needs, and not for children who have special privileges.
Supposing that were the case, does anyone have any advice on multiple testing?
I would imagine the district is keeping current on the research on bilingualism and second language development, including the median years to cognitive academic language proficiency, which is what is assessed on the kind of measure that shows up in gifted screening. The work of Jim Cummins has been around for decades, and continues to be the foundation of most thinking on second language acquisition. Granted, the trajectory may be somewhat different for the gifted than for NT ELLs, but the generally accepted range is 5-7 (some say up to 10) years to CALP, even though surface/social fluency (BICS, or basic interpersonal communication skills) can occur as early as 2 years in. How this all interacts with the language learning window in preschool and primary-age children is another factor.
Moving on to your actual question!
Given the usual years-to-BICS and years-to-CALP, I would say that re-testing after two to three years of formal instruction in English monolingual settings would make sense for a presumed GT kid. (Assume a verbally-gifted child makes progress in English acquisition at a rate proportionate to his verbal gift, so say, at least 1.5 times the pace of an NT age-mate; five years divided by 1.5 is about three years. A nonverbal-only gifted child won't reach the cutoff score in verbal testing anyway, so we won't worry about the slower pace of English acquisition.)
This doesn't, of course, account for the cultural differences in early environment which might be correlated with ELL status, and which will likely not be overcome as easily in three years of schooling. There is a reason other systems (notably LAUSD, largely as the result of lawsuits) use matrix reasoning tests (Raven's, NNAT-2), which have evidence supporting more equitable, less-culturally-laden, selection outcomes.
