Reminders to be send on number of workday days from initial date

[MarioOne]

I am working on SharePoint List solution that acts on date trigger.

The base date is a date of parcel receipt. This date is my Initial date.

I need a set of reminders that stop once Picked field is turned "yes".

Idea here is:

• Notification mail info on "New Item" - done and work fine
• Flow to send reminders on 2nd, 4th and 7th working day from the initial date (parcel receipt) 
• Fields Reminder 1, 2 and 3 to be updated by the flow accordingly with the date of reminder

After numerous tries with various flow parameters, my reminders are still failing to execute as required. Most common failure is related to the date the Reminder puts on the list. The dates, are not following the designated standard, but their chronology is mixed. 

My flow for Reminder 1:

Function there is: and(greater(dayOfWeek(utcNow()),0),less(dayOfWeek(utcNow()),7))

My condition is:

I am struggling to create a flow that will meet above criteria and execute on each record respectively.

Solution I believe will solve that would need to be constructed with following elements:

1. Schedule run every 1 week on workdays (Mo-Fri) as Initial trigger
2. Get items filtered ODATA Picked eq No
3. Condition on Arrival if greater or equal Today -X (X a number of days for reminder)
4. Send reminder email to Parcel Recipient
5. Update List for Reminder 1 Field

My biggest concern is step 3 as I am lacking at the moment formula writing skills. Can you suggest a formula that can fix this issue?

I come across Add Days function but not sure on how to use it. I would love to hear from you.