May I refer you to the MackerelWatch UK post. This post should tell you where mackerel are being caught around our coast. If Edinburgh isn't shown I would imagine they aren't there yet. However they should be around soon as there are plenty in Methil and Burntisland. I tried Granton in June but a little prematurely I think.
If you look at the M/watch post twice a day for the next 14 days you should find a cure.
doug try the breakwater at the sewage works you can fish at the back of the sewage works no problem it has a clean sandy beach a few snaggy marks. fish near the big gas balloon you cant miss the site also try along the breakwater near portobello .cheers andy sorry forgot to say the leith sewage works.