Delay time ARX with delayest

I have to estimate the delay time of the following model which has 3 inputs:

I have found the built-in function delayest but matlab keeps returning this error and I cannot figure out how to fix it:

Error using delayest (line 86)

The combination of delay limits will result in 64000 delay-combinations, which is
more than the allowed number of tests (10000). Either make the delay span more
narrow or increase maximum allowable tests using the sixth input argument of the
"delayest" command.