When to add the spices in extract brewing?

I have only been brewing extract, and have focused on Belgian Wheat Ales (Wits) like Shock-Top, Blue Moon and Hoegaarden clones.

I want my brew to be more citrus tasting than it is (even compared to the originals). I noticed some recipes call for adding the spices (coriander seeds, bitter orange peel, sweet orange peel, lemon peel, lime peel) depending on which brew - for the last 10 min of the 60 min boil or for the last 5 min of the 60 min boil.

If I want the most citrus taste, should I do the last 10 min or the last 5 min of the 60 min boil? I have also started leaving in the spices in the primary fermenter to see if that also helps add more citrus taste to the brew.

Just a suggestion but I get a real citrus taste/aroma from dry hopping. Try an ounce of Citra, Amarillo, or Cascade for a week after the beer has reached final gravity. The only downside from dry hopping is that it starts to fade away in 2 or 3 months and is pretty much gone in 6 months.

I've used spices & zest the last 10-15 minutes of the boil. but dry hopping with them as well might boost them a bit.

putting your spices in the last 5 minutes or so is good. You can also do sort of a "hop stand" with the spices/zest too. Basically after your boil is done let the wort cool down a little, to about 190-180, drop your spices/zest in and stir. Let it sit there anywhere from 15-30 minutes. I've done this with hops before and it works well to extract flavor. IDK if it'll do the same with spices/zest but I guess it's worth a shot. Since you're using extract you could even make a couple super small batches and experiment with the 'spice/zest stand' and see what works best.

Another thing you can do is to dry hop with citrus zest. When you pitch your yeast also soak your zest in a jar full of vodka. Put the zest in a muslin bag or something and let it soak for a week or so. Once the beer is finished fermenting dump the jar of zest and vodka into your beer and let it sit for another 7-10 days. You wont need very much vodka. Use an old jelly jar or something small- just make sure the jar is sanitized, the vodka will sanitize the zest. The vodka will extract the flavor and add a little nose to your beer too.
Good luck!