Buy a large plastic bottle of baby powder from your favorite supermarket, makes things so much easier if you cover everything with it, inside tyre, flap and tube. A bit of towel works well for spreading it about.
It may puff out when you inflate, so get the unscented to avoid funny looks...
Some fitters like to inflate and then fully deflate the tyre, this lets tube and flap relax, so on final inflation any folds or tucks should disappear, makes sense to me..