Should be enough if it's direct and not filtered. Stagger planting a week or so apart.

The glad florets start blooming from the bottom up and each floret will last a few days

What is the minimum bulb size to look for to increase my chances for a nice 1st year bloom ?

Whenever I grew glads, I just bought the prepackaged Grandiflora offerings from one of the Big Box stores or a hardware store... and for three reasons: 1- they're inexpensive and readily available; 2- they're packaged as single colors or as a mix; 3- they always grew and bloomed beautifully.

I'm not tempted to mail order (nothing against it, I just don't) since I generally didn't dig and store in the fall, but started fresh when wanted. The inexpensive over the counter bulbs are of the size to produce good plants and blooms. The packages are labeled Grandiflora and those have the large florets.

If you buy from a box store be sure and buy early and store in cool place until time to plant. Many big box stores get them months before planting and they dehydrate on the shelf. If you really like glads check this website. www.gladworld.org

I have bought from Dollar General and didn't plant for 3 months. I still get great blooms. Glads are really tough. However, I live in the deep south so you have to take in to consideration what zone you are in and your climate.