It’s not as safe as you think. In normal situations, market orders fill almost instantly.
If the market drops below your threshold due to major news, like the Covid shutdowns, your sell order will enter a queue. Depending on the ability of your brokerage to execute orders in competition with the rest of the market, your sell order may complete quickly, or not. You’re potentially taking a huge loss.
I’d recommend building up your savings account. Getting more than 4.5% in a risk-free HYSA is an easy choice in this case.