This is not the last day to buy a bitcoin, because the price could fall and so far have not seen signs of halving. You should continue to monitor if you want to buy, when it is foreseen to rise, it is a good time to buy.
May be we won't see too high price at halving as price is not moving as per the expectations, but I feel price will go higher after few months of halving, so if you can wait till that point, then this is the good price to buy.
I have bought bitcoin under $500, and my goal for halving. so I will not buy for now, it is too risky for me. because I would sell when halving occurs and no increase. then wait for the re-buy when price drops.