Experiencing some minor shifting. Last aligner okay to use if retainer is worn out?

So I've been done with invisalign for about a year and I have noticed minor shifting back in my top front teeth which I use a thick plastic retainer which I received after treatment. However I have grinded holes in the retainer and it no longer feels as tight. I have an appointment to egg a new one in Monday, but I was wondering if I should wear my last invisalign aligner (which still fits) 24/7 until Monday or should I continue to just sleep in the thick plastic one that I am replacing?