Hi @Sativaindica,
With respect to loading of your outlets, is important to know what those LED fixtures actually draw in terms of current. Nearly impossible to tell from the advertised wattage.
I have two LED fixtures, both advertised as 300W. One is 180 actual watts, the other is 120.
Most household circuits are on 15A breakers, which means 1800W maximum power at 120V. We usually design connected load to not exceed 80% of rated branch circuit capacity, so your real life maximum is 1440W per circuit, or about 12A.
Another design parameter is how many outlets the engineers/electricians put on one power circuit - that number is usually 5 for dedicated power circuits, I am not sure about residential designs because sometimes your overhead lighting and power are run off the same breakers. So just because you are using a different outlet, does not mean you are using a different circuit, so find the one that is on a different breaker if you have to.
As for those plug-in timers, they are kind of crappy, I would not load them with too much. If in doubt use more if them. LED fixtures have a pretty high inrush current, many times higher than their rated capacity, so contacts and circuitry in crappy timers may not last long under full load.
Good quality, high-Irish stable devices will actually use a solid state switch, like a TRIAC, to start the load momentarily, and then switch the relay under zero potential, to prolong the life of contacts.