We (in a group of 12) visited Valley of Flowers and Hemkund Sahib in the 1st week of September. The itinerary is the same as available at most places over the internet. Haridwar->Govindghat (Day 1)-> Gangaria (Day 2)->Valley Of flowers (Day 3)-Gangaria>Hemkund Sahib (Day 4)->Govindghat (Day 5). But I have a couple of important points that might help:
1. Time of Travel-> Although famous travel sites will say July- Sept is a good time to travel to VOF, don't expect the bloom after 15th August. 1st week of August is the best time to travel if you are a sucker for the bloom. Having said that, even minus the flowers, the trek is beautiful.
2. Food supplies- Hemkund Sahib is no problem in terms of food supplies as there are multiple food stalls and rest points along the way. For Valley of Flowers, however, you need to stock well. There are no food stalls/ washrooms etc on the entire trail. We started our trek at 7 AM and reached the valley entrance around 12 noon. You need to carry food for the trek from Ghangaria itself.
3. Road Travel to Govindghat- If you start your travel from Haridwar/ Rishikesh early morning, you will reach Govindghat same day late night. However, you must note that you must cross Joshimath before 7:30/8 PM. Around that time the roads are blocked and you may need to seek special permissions from the local police to travel beyond, at your risk. It is also risky to travel once its dark.
Drop in your questions, if you have any. Will try my best to answer.