What you are trying to do is possible, but you’ll need to track and report the interest you earned during the time the GIC is outside of the TFSA.
For example, imagine a 1 year GIC that is opened in January (simplest case). Suppose you kept the money invested in the TFSA until June, but then decided to transfer the money outside in July, you would need to report the interest that was accrued for July to December on your tax return.
Problem is your bank/broker will probably give you a T5 for the full amount because it matures outside your TFSA. (If they even let you do this at all). A copy of the T5 will automatically go to CRA. And unless you are a multi-million dollar customer, and you are supported by an accountant, your bank/broker won’t likely be willing to adjust/prorate your T5.
I recommend you keep it simple and just wait until the GIC matures.
Also for tax efficiency, consider that outside of an tfsa/rsp, interest income has a higher marginal tax rate than either dividends or capital gains.