Example on how to look for the date based on a day of the week

main.go

package main

import (
	"fmt"
	"time"
)

func main() {
	t, _ := time.Parse("2006-01-02 15:04", "2021-05-17 10:55")
	today := t.Weekday()
	now := time.Now()

	day := time.Sunday
	var next time.Time
	if day == today {
		hour := now.Hour()
		reqHour := t.Hour()

		if hour >= reqHour { // if hour is now, or equal provide next week
			next = t.AddDate(0, 0, 7)
		} else if reqHour < hour { // calculate tomarrow instead of today
			next = t.AddDate(0, 0, 1)
		} else { // today !!!
			next = t
		}
		
	} else if day > today {
		next = t.AddDate(0, 0, int(day-today))
	} else {
		next = t.AddDate(0, 0, int(day+(7 - today)))
	}

	fmt.Println(t, today, day, next, next.Weekday())
}