We used Gardengrocer a few weeks ago, and were very pleased! I'm pretty sure wegoshop charged more for the delivery fee, and that was our deciding factor. Gardengrocer delivered on time and everything was exactly what we ordered. I will definitely order from them again.
I would probably order a week and a half to two weeks ahead of time. I noticed they would have signs on their website that, due to high volume, they weren't accepting orders for upcoming dates. So, order ahead of time to avoid that disappointment!