It depends on a lot of things. This is a pretty broad question with lots of pieces. Rob Walling has a great course on Udemy on The Startup's Guide to Virtual Assistants. The course costs $99 and it's more focused on VA work than straight dev / coding but it touches on both. I took it and it was worth every penny. https://www.udemy.com/startups-guide-hiring-virtual-assistant-va/
I don't think it's a case of outsourcing to a specific country (i.e. India vs Vietnam vs anywhere else), as much as understanding that outsourcing has its benefits (costs mostly), but also challenges (project management / communication).
My best recommendation is to use a service / platform like Odesk (http://odesk.com) when outsourcing any work. They assist both in tracking the work done (especially helpful when you're being billed per hour) and also in resolving issues (if your supplier screws up).
I agree with Adii. It's not about which country should you outsource to, but about outsourcing itself.
When you are bootstrapping to launch your venture, pool in all your funds, keep the costs low and go with an outsourced provider that understands your requirements best. I understand the predicament that you may have with regards to outsourcing, but the most important thing for you at this moment is to get your product out there.
Once you have a Beta going, maybe go in for funding, scale it up and hire a team who can then carry it on from there.
Some of the most famous products today were outsourced in their initial days – Alibaba, Fab.com (to an Indian company), Digg, Skype. And these are only a drop in the ocean of such examples.
The location is less of an issue than the fact that outsourcing brings with it a bunch of complexity and can require a lot of attention and management. Time zones, culture, timelines...all of these add challenges that go away when your team or providers are close at hand. Not to say it can't be done, but don't think that it will be super easy.