Keeping on working while you run the orphanage is not impossible. It all depends on:
How many kids you have
How many employees you have
Whether or not you can get assistance from any other NGO’s (i.e. finance/volunteers)
Our suggestion would be to start out VERY small. No more than 2-4 kids. Try it for a year or two; work out the boundaries you need to set in your life between work and the orphanage: your old family and your new family.
There are loads of stresses & lifestyle changes that come with having a regular child -let alone 2-4 children who might have spent anywhere up to 15 years living on the streets! Don’t rush into anything as sustainability is what is important. It is better to help 1 orphan for their whole life than 1000 orphans for just a few months.