A short debrief:
Approximately 3 months preparation time, as I couldn't get test date on time.
Target score: 680 - 690
Prep:
Quant: Gmat Club math book +
gmat club tests + OG13 + OG additional question sets
Verbal: Artistole verbal set + OG13 + OG Verbal Review + OG additional question sets. I think this is enough material as I used to score as per my target, V35, but I messed it up on test date.
Prep Scores:
GMAT Prep1 : 680 Q50 V31 (after preparing for 15days)
Veritas Prep1: 690 Q48 V37
Gmat Prep2: 680 Q48, V34
Mgamt 1: 670 Q46 V35
Gmat Prep3: 670 Q48 V34
Gmat Prep4: 710 Q49 V38
Actual Score: 640 (Q50, V28)
Analysis:
1. I travelled a day before test as there is no test center in the remote part of Norway I live in, so flew to Copenhagen previous night. This proved to be disastrous that too a travel late in the evening

To add to it, I couldn't sleep well in the hotel room I booked

This was the closest hotel to the test center

2. Test center setup was horrible. For prep and mock test I used most comfortable chair and seating arrangement with lot of space. Test center chair was like a baby chair for my size

and very crumbled space arrangement. Couldn't do anything as all the chairs were same and all cubicles were same.
3. Probably I used lot of caffeine

Not sure about this but this can be a contributing factor.
4. After quant probably I was bit overconfident; again not sure about this but it can be a contributing factor.
5. Test center Key board was horrible; I thought I messed up AWA with many spelling mistakes but finally scored 5. Realized that it is very easy to score on AWA

Currently I am planning future course of action as I am looking for the executive MBA and I hope this score is just meeting the EMBA requirements.