Firstly I think
best option and
safest option are two very different things! The best option could well have been to buy Bitcoin at $15.5K, or even start of the year based on Bitcoin's 4 year cycles, but only time will tell if this turned out to be the best price or not. Buying into a bear market reversal isn't the worst idea, which arguably by many metrics was around $22K/$23K, or otherwise re-testing $20K as support.
The only issue with right now with price around $28K is that it is right below previous support that could well end up being confirmed new resistance. If anything there is a better argument for waiting for things resistance to be breached and buying >$30K if you're wanting to play it safe, or otherwise a correction to $25K in order to turn it into new support. Between $25K and $30K is a bit of gray area.
Ultimately dollar cost averaging is one of the best and easiest ways to accumulate Bitcoin during a bear market. For example if you had done DCA for past 300 days since June when price was under $30K, you'd have an average of around $21K, which right now is looking quite healthy. Or even since BTC initially broke $30K 330 days ago in 2022, it'd still be under $22K. Or even since Bitcoin was 50% down from it's highs around $35K, dollar cost averaging would still be under $22K. It might be a bit late now to be suggesting DCA in a bear market now price is reversing, but food for thought for next time maybe!
Others will tell you that the best day to buy Bitcoin was yesterday, which while true in a bull market, is probably the opposite in a bear market. In a bear market, the day after is probably a better day to buy