Oil pressure question

I just did a timing chain on my 1987 Gn. I packed the oil pump with vaselene. Can I run it till the next oil change or do I have to change the oil right away. Also, what's the easiest way to make sure my oil pump is working, is there a simple way to check if my oil light is working?
First turn the key on without cranking the engine. The oil light should be lit. Once the pressure sensor sees 4PSI the light goes out.

Also, if you put a roller chain (or any chain with a rough OD from 'dogbone' shaped links)... put the timing cover back off and remove the tentioner assembly before it ends up in the oil pan.
I always use a drill & prime tool on the oil pump after the cover has been off. You can feel the drill load up when oil pump primes then rest assure you have oil pressure when you start the engine.
These days that's more than common. The stock set would last a little over 100,000 miles. Perhaps, pop the cover off and swap it out for a new one in 50,000 or so.