It is NOT a good idea to spray the whole garden with spinosad. It's organic, yes, but you'll kill everything. It's particularly hard on bees
. It's to be used topically, where needed ONLY. An organic garden is a balancing act, in which your beneficial insects are busy eating the harmful ones. Spinsoad, neem, and others, they are all best used to combat specific pests on specific plants. If you broadcast the spinosad around the garden you just hit them all, knocking out the balance in the garden.
Go ahead and put the seaweed on whenever. The harm is done. I would suggest using some Thrive (water it into the soil, it doesn't go on the plants) to add Mycorrhizae to boost the nutrients available to the plants (here is an article about that
). If you have plants that are under stress they tend to attract pests. Let the beneficial bugs come back, maybe buy some ladybugs to release in your garden.
Organic products aren't meant to be used in the same way the chemical pesticides are advertised to be used - you don't just overlay the yard with a chemical fog and remove all insects. This is an important message for any gardener new to organics - there is no easy fix, no one-stop shopping for pest control. The most important part of organic gardening is that you need to learn about the insects and organisms in your yard, and you have tolerate a certain number of pests if you want a really healthy garden that is good for food or ornamentals.