affix: delay for first checkScroll
affix: delay for first checkScroll

- sometimes the first scroll don't take effect. added a little delay

BiodataMiningGroup/vue-strap,tonypee/vue-strap,tonypee/vue-strap,lotestudio/vue-strap,BiodataMiningGroup/vue-strap,lotestudio/vue-strap,wffranco/vue-strap,yuche/vue-strap,yuche/vue-strap,wffranco/vue-strap