Spring. Early spring for cool season grasses and later for warm season grasses.

I have some Lemon Grass seed and some Miscanthus Sinensis seed. Can I start these indoors and set them out in the spring? Or, is it even necessary in zone 8b? If starting indoors, when do I start them and when to transfer to the garden? These are teeny tiny seed so would rather start indoors and set out the seedlings where I want them. Sowing directly into the bed seems way to chaotic and gets more plants where I don't want them. Advise??

It's better to start a new thread with questions like this, rather than tagging them onto a thread with an entirely different subject.

You can certainly start your seeds indoors. Lemon Grass takes 3-5 weeks to germinate at 70-75°F. Miscanthus is about the same, but may take longer, and is very erratic in germination.

The Lemon Grass will almost certainly come true to the parent plants, but there's no telling what you'll get from the Miscanthus. If the Miscanthus seed is species, and not a cultivar, you'll probably get a good result, but it is known for throwing out odd variations. Miscanthus spp is also known to be quite invasive in climates like yours. I pull thousands of Miscanthus volunteers every year, because I wait too long to deadhead my plants. It will be worse for you.

When you transplant the seedling to the garden is up to you. Both require quite warm conditions to get good growth, but unless you have unusually cold weather, transplanting early won't hurt either one. My Miscanthus doesn't really take off until mid-July. Lemon Grass is about the same.