Copy Excel file and make multiple daily versions

Question

Every month my department has to generate blank upload files (xlsx) for each day of the month.

The following code helps this process by copying a template, iterating through the number of days of the current month, and generating a file for each of those days from the template.

I found the copy_rename function which helped a ton.

I'm looking for any feedback pertaining to:

1. Can I avoid the format_Num function somehow?
2. Do I need to .close() the file, since I didn't open it?
3. Layout of the code: can I have my functions at the very bottom so that the code comes up first?

# checks whether a number is single digit or not
def format_Num(num):
num = str(num)

if len(num) == 1:
    return(str(0) + str(num))
else:
    return str(num)

#function copies a file from one dir, to another

def copy_rename(old_file_name, new_file_name):
    src_dir= "C:\\a\\dir\\Desktop"
    dst_dir= "C:\\a\\different\\dir\\TESTPYTHONFILES"
    src_file = os.path.join(src_dir, old_file_name)
    shutil.copy(src_file,dst_dir)

dst_file = os.path.join(dst_dir, old_file_name)
new_dst_file_name = os.path.join(dst_dir, new_file_name)
os.rename(dst_file, new_dst_file_name)

from calendar import monthrange
import shutil
import os
import datetime

now = datetime.datetime.now()
curr_year = now.year #2018
curr_month  = now.month #04

total_month_days = monthrange(curr_year, curr_month)[1] + 1
filepath = "C:\\a\\dir\\Desktop"
template = "Template.xlsx"

for day in range(1, total_month_days):

wb_Name = "workFeed" + str(curr_year) + format_Num(curr_month) + format_Num(day) + ".xlsx"
path_n_fileName = os.path.join(filepath + wb_Name)

# verifies that the file does not exist    
if os.path.isfile(path_n_fileName) != True:
    copy_rename(template, wb_Name)