First off, I've never had any problems when the credit card was available.
Second, Ikea does not provide the credit, it is a bank... in most cases it was GE Money.
Third, credit card payments that are being paid via electronic check, usually take about 3 business days to clear... So even if you pay the night before, it will still take 3 days to clear.
I always pay my credit cards, 2 weeks before the due date. Never had a problem.
Learn to read the terms and agreements, it says a lot in that tiny print...
I hope the credit card comes back... hopefully not through GE Money...