Dynamic Day Increment on Repeater - filamentphp

Question

I want to increment the number of days for every new repeater. Day 1 , Day 2...

Repeater::make('itineraries')
                    ->relationship()
                    ->schema([
                        TextInput::make('day')
                            ->default(function ($get) {
                                return collect($get('itineraries'))
                                    ->pluck('day')
                                    ->count() + 1;
                            })
                            ->required(),
                        TextInput::make('title')
                            ->required()
                            ->placeholder('ARRIVE KATHMANDU'),
                        Textarea::make('description')
                            ->required()
                            ->placeholder('It is a panoramic thrill flying into Kathmandu on a clear day....'),
                        TagsInput::make('available')
                            ->separator(',')
                            ->placeholder('Check in and Overnight at Hotel'),
                        TagsInput::make('unavailable')
                            ->separator(',')
                            ->placeholder('No meals'),
                    ])

I tried the official documentation way https://filamentphp.com/docs/2.x/forms/fields#using-get-to-access-parent-field-values

i.e.

$get('../../day')

But this also doesn't work. Help!