I have found DomainNIC to be exceptionally fast at updating nameservers and such and prices are low so I've started using them for purchasing .net and .com addresses but still have other sites I use for .co.uk and .co domains.
To get started visit DirectNic.com
Login to DirectNic.com
Click on My Services
Then Click on Domains
Once loaded you'll select your domain and change nameservers
ns01.000webhost.com and ns02.000webhost.com
Are the required nameservers for any domain you wish to point at 000webhostapp content.
Now my nameservers have updated successfully.
Once you submit it can take a few minutes for the changes to take effect but if you visit your 000webhost.com control panel you should be able to park your domain hopefully.
You'll want to visit "Set Web Address"
Then click add domain at the bottom
In this case I am using nameservers and not CNAME record pointing.
I have typed in my domain I purchased over at DirectNic
Hopefully the DNS have progressed the changes so 000webhost can see the nameservers are pointed at it.
Has appeared top right so that means that the domain has successfully parked and pointed correctly.
I will now select "Link Website" to set my website to the correct 000webhostapp account on my control panel.
Select the content you wish to load when someone visits your website.
I have successfully pointed my domain from DomainNIC and parked it correctly at 000webhost
Now it is time for me to make my website and upload it.
If you have any questions do reply!