Many finos tend to lose freshness and become a bit stale when they are
stored for several years. In the US I try to buy fino from a store that
has good turnover and drink it soon after purchase.

I would just stand the bottles up for several days or a few weeks to
hopefully allow most of the sediment you mentioned to fall to the bottom
of the bottle. Then pour or decant the fino very carefully. There is
considerable variation in brands of fino, so it is difficult to guess
what kind of shape it is in. Most of the best finos are quite dry, often
are best somewhat chilled, and can be drunk with a wide variety of foods
as well as alone.

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