How to exclude Mondays and set minimum date in date picker?

[SamRDCA]

Hi there. I am having difficulty getting the date picker on this form to omit Mondays and select the min day 3 days out from "todays date". https://nuflours.com/pages/test-pick-up-form

Here is the code below. I have it on the page but also in the theme.liquid and it does not seem to be working. 

<script>
window.onload = function() {
if (window.jQuery) {
let $ = window.jQuery;

$(function() {
$("#pick-up-date").input({
minDate: +3
beforeShowDay: function(date) { var day = date. getDay(); return [(day != 1), '']; } }) });
});
});
}
}
</script>