I am writing this based on what actually happened with me, in short full details about Family Visa. I would also highlight some common myths which are not true.
1. There is no rule of 6 month waiting time for family visa, this all depends on PRO of a company. So don't think too much on this and by reading various topics don't take tension.
2. You need to get your marriage certificate Apostle from Ministry of foreign affairs. This can be best done when you are in India, However if you forgo to do this, you can do it in 2 ways -
Use local people who get this done but charge like 50-60 Riyals.
Or courier it to agencies in India and they charge 2500 Rs per document and courier us back. This is cost effective but takes approx 15 days including both side post time etc. (I used this one.) Also it is better get your degree done as it might be required later on, not for visa but for designation change etc.
3. You will need a rent agreement, there is no timing defined as such but minimum 6 months would do.
4. Photographs are required as per regular rules which everyone knows.
5. GAMCA medical report
6. Any one who has got more than 600 Riyal Salary can get their family. There is no rule for designation as such as many people say that your designation must be engineer or higher which is not true.
7. Your visa copy, Passport Copy, Resident Card Copy
8. Wife & Kids Passport copy.
9. No need of birth certificates of kids
10. Both husband & wife should have their name endorsed in each other passport.
11. No bank statement is required as if required company will put by themselves a salary transfer letter.
12. Give all these to your PRO and he will do the rest.
13. Processing time is from 5 minutes to 2 weeks, as I got my family visa in 5 minutes.
So in short before you decide to move to muscat, make sure you speak to your HR regarding family visa status and its only once your HR approves, PRO will do it and it is possible that if you negotiate well you might get family in 2 or 4 weeks after you come, but generally as 3 month is kinda probation it is advisable to plan family after that as you also should feel that Muscat is good place to go longer or not.
That's it from my side, in next I will write about Driving license which I am going through and about schools also about what to carry & other Do's and Don's based on what I have seen.
Feel free to ask if you have any queries which I can answer based on my info. All the best.