We plan to launch FedNow instant payments in December, but the core team's real-time balance and debit API won't be ready until February. The business MD insists on a December launch. We expect about 10,000 outbound payments a day averaging $300. The interim option checks balances using the prior end-of-day balance minus today's posted transactions, and we estimate about 0.5% of payments would go through without sufficient funds. What would you recommend?

我们要在 12 月上线 FedNow 即时付款，但核心团队的实时余额扣款接口明年 2 月才能交付，业务 MD 坚持 12 月上线。预计每天 1 万笔外发、平均 $300。临时方案是用日终余额减去当天已记账交易来判断余额，测算约 0.5% 的交易会在余额不足时被放行。你怎么建议？