side note: CD's are terrible, terrible tools for investing. You are losing money, with inflation, usually.
to OP: Go part-time whenever you want. If you're not relaxed, happy, enjoying every day, then it's time to change jobs or careers and find what truly does make you happy.
I was full-time +overtime most weeks with Walgreens as a floater. I was burnt out, and my numbers (errors) were showing it, and there was absolutely zero upward mobility for me there, despite 5+ attempts at different locations in my metro to become a manager or staff. I went to a LTC pharmacy as part-time salaried rated for 35 hrs/weekend @ $105k/year but lost retirement and health ins is more expensive now, ~$600/month. I still probably work on average around 38-42 hrs, now a year later, but it's worth it. Go PT, enjoy life, travel, relax awhile, volunteer doing something around town, or at a school, get involved at church... Go back to FT later.