Eating fish such as salmon is generally recommended twice a week. If you eat two servings in one night, or say servings in back-to-back nights, are you not benefiting as much?
There is no known ideal time window. If you supplement there is some evidence it’s better with meals.
FYI due to how fatty acids are metabolized it’s ideal to get DHA & EPA every day. If you supplement you just skip it on days you eat oily fish.
Supplements are generally 500-1000mg of omega 3. The average farmed salmon portion is ~1800mg.
If you can eat 2-3 servings of tuna a week (which is the recommended limit), then you can eat about 10-30 servings of salmon a week. Depending on the type of tuna, mercury is .144 (chunk light)-.689 (big eye) ppm.
Salmon is 0.014-0.022ppm. Source: FDA
Depends
Are we talking farm raised Atlantic salmon ? Or wild sockeye?
I take fish oil everyday and still take a full dose on days where I have eaten Atlantic farm raised salmon, however I will typically take 1/2 dose on days where I am eating wild caught sockeye as it has much higher dha/epa levels than farm raised.
Either way, if you do take in more omega 3s /epa-dha than what’s recommended every once and a while it’s not going to harm you.