Help with recurring dates on Django project

This is my first post so please be gentle a newbie at coding and Django,
I have created a view that when a job is created there is an option for the job to reoccur every 4 or 6 weeks, the problem is when I create the job the 2nd occurence is 8 week from the intial date and then subsequent dates are in 4 week period like below, hope this makes sense
Jan. 1, 2023 Every 4 weeks
Feb. 26, 2023 Every 4 weeks
March 26, 2023 Every 4 weeks
April 23, 2023 Every 4 weeks
here is my views.py

**def create_job(request):**
**    form = JobForm(request.POST or None)**
**    if request.user.is_authenticated:**
**        if request.method == "POST":**
**            if form.is_valid():**
**                job = form.save()  # Save the job object**

**                # Calculate the invoice amount**
**                amount = job.cost**

**                # Calculate the next occurrence date based on the selected occurrence frequency**
**                if job.occurrence == 'Every 4 weeks':**
**                    next_date = job.date + timedelta(weeks=4)**
**                elif job.occurrence == 'Every 6 weeks':**
**                    next_date = job.date + timedelta(weeks=6)**
**                else:**
**                    next_date = job.date  # Default to the job date if no valid occurrence is selected**

**                # Check if an invoice already exists for the next occurrence date**
**                existing_invoice = Invoice.objects.filter(client=job.client, date=next_date).exists()**
**                if not existing_invoice:**
**                    # Create the invoice with the next occurrence date**
**                    invoice = Invoice.objects.create(client=job.client, date=next_date, amount=amount)**

**                messages.success(request, "Job created successfully")**

**                # Create occurrences for the next 5 years**
**                if job.occurrence == 'Every 4 weeks':**
**                    for i in range(1, 195):  # Create 195 occurrences (5 years)**
**                        next_date = job.date + timedelta(weeks=4 * i)**
**                        existing_invoice = Invoice.objects.filter(client=job.client, date=next_date).exists()**
**                        if not existing_invoice:**
**                            Job.objects.create(job_type=job.job_type, client=job.client, date=next_date, occurrence=job.occurrence, cost=job.cost)**
**                elif job.occurrence == 'Every 6 weeks':**
**                    for i in range(1, 130):  # Create 130 occurrences (15 years)**
**                        next_date = job.date + timedelta(weeks=6 * i)**
**                        existing_invoice = Invoice.objects.filter(client=job.client, date=next_date).exists()**
**                        if not existing_invoice:**
**                            Job.objects.create(job_type=job.job_type, client=job.client, date=next_date, occurrence=job.occurrence, cost=job.cost)**

**                return redirect('job_list')**
**            else:**
**                messages.error(request, "Error creating job")**
**                print(form.errors)**
**          **
**            else:**
**            return redirect('home')**

**            return render(request, 'create_job.html', {'form': form})**
**```**
thanks for any guidance

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