How should I purchase Vanguard S&P 500 stock?

Looking to put ~£10,000 into the S&P 500 via Trading 212 app.
Plan to invest into the accumulative version that adds dividends back into the shares automatically.
Should I set-up various 'Limit' targets to buy stock at 67, 66.5, 66, 65.5, etc or use some other method?

If I'm missing any details, let me know & I'll edit the post.

Looking for some suggestions, thanks!