We study a problem of sequential frame detection in an asynchronous framework, where a single frame of length $N$ slots is transmitted uniformly in a large interval of known size $A$ slots. In this setup, we seek to characterize the scaling needed of $N$ and the channel (input) parameters for asynchronous optimal frame synchronization. We note that the framework permits a natural trade-off between $N$ and $\alpha $ , where $\alpha $ is the synchronization threshold of the channel (usually parameterized by the channel input). We present a general framework that permits this trade-off and then characterize the scaling needed of both $N$ and $\alpha $ as a function of the asynchronism period $A$ . Finally, we apply our results to the AWGN channel as an illustration.