const checks = document.querySelectorAll('input.form-check-input')
checks.forEach(c => c.addEventListener('click', onClick));
function onClick() {
const res = [...checks].filter(c => c.checked);
if ( res.length === 3 ) {
const url = 'http://site.ru' + res.map(c => c.value).join('');
location.href = url;
}
}