I'm scared of staining my new patio when grouting. Any tips or stories?

Laid Indian sandstone and next is to put the dark grout in. Before beginning I thought I'd research how anal I have to be to ensure none remains on the surrounding slabs (as to me just a quick brushing won't remove every particle/grain of the grout) and have gone down the rabbit hole of seeing posts about stained slabs.

Now I've also come across one thing saying seal before grout, but when looking into sealing and why I've seen barely anyone does it (one person's quotes 5% of people seal their patio but I've no reliable source for it) and the stuff on sealing talk about doing it after grouting.

What can my fellow DIYers inform me about experiences of grouting a patio, cleaning it to avoid stains or steps like sealing that I've not thought of till now?

My biggest fear is cocking it up after all this time and effort.

For info: Kandla Grey Indian sandstone slabs Sika FastFix joining compound charcole (please don't make this a discussion about grout options though)