We have had this before, when the plant is young and has not established much roots.
The perlite can clog up the hole and prevent the flow, so the pencil will open it up
Dr. Jekyll
Assuming your drain hole is big enough you should have no issues within a week as the roots will hold the perlite in place
You will also notice some perlite will escape with the drain water, nothing to worry about, as this is a normal at first.
People will use large perlite which will help this issue, but we don't bother as the cost is a fair bit more than normal perlite, so instead we mix in a bit of vermiculite
Mr. Hyde
