12 weeks is good enough imo. Deca has such a long halflife, I usually only run it for 10/12 weeks and I'll notice my strength keeps going up even after I stop pinning. Week 13/14 I still feel it/see results. I'd go 400/500 test and 400/500 deca. And eat like a horse. The amount of food will dictate the mass you put on. Look into on cycle support... I'm not sure what you take for deca. I've never needed AIs or meds for progesterone related sides. The only gyno symptoms I've ever noticed have been with deca and dbol. If you're sensitive to side effects, you wanna be safe. You could start with test prop to kickstart. See some results right away.

In my opinion 10-12weeks for nandro is a bit short. Nandro is better for longer cycles, maybe with cruise and HCG in between. But as Makwa says, depends on your cycle history. If you are a newbie, I wouldnt recommend nandro for the second cycle..

If first cycle is Test only, for second cycle I would add for example stanozol or dbol. I think nandro is not for newbies.

But to answer, I would go higher on Test and go for like 200-250 nandro a week at max. Maybe Im just a pussy, but I dont for high dossages ever even tren 200-250/week at max. Sometimes less is more ;)

cycle history?