What to set first? A campaign or an automation, while getting started with Klaviyo?

Hi there,

Suppose I am a Shopify Store owner with about 50,000 email profiles who have opted-in to receive marketing emails from me either through Shopify’s sign up form or while checking out. 

I want to upgrade my email marketing and get a Klaviyo subscription. 

Next I integrate my Shopify store with the Klaviyo account so that all historic engagement data (i.e., opens, clicks, etc.) is taken up by Klaviyo. 

I build my 30 day engaged segment following the Klaviyo guide. Suppose the outcome is 5,000 profiles who have engaged in the previous month. 

The question is…

What should I do next? 

Should I send a campaign to these engaged profiles? 

Or should I first set up high engagement flows like welcome series, abandonment cart, browse abandonment etc?

In the “How to ramp and warm your sending infrastructure” guide, judging from the order of numbering, it looks like we should send a campaign to the engaged segment first. 

Also, the same document suggests that we should set a welcome flow after 14 days of sending campaigns from Klaviyo. 

But due to some concerns I had a bit of confusion regarding whether to set a welcome automation first, or to send a campaign.

I wondered if the email providers like gmail etc would let me reach the inbox of those 5,000 profiles in the first campaign send. 

Maybe I’m assuming things here; but remember we are starting with a new Klaviyo account? So how would the email providers know if I’m a good or a bad sender? And if they don’t know this, wouldn’t they move my campaign to spam?

Although I’m hoping that I’m wrong, but since it can seriously damage my sending reputation if otherwise, I wanted to be sure by asking here. 

And if a campaign is to be sent first, should we then keep sending campaigns (acc. to our business needs) in the first 2 weeks directed at warming and ramping up our sending infrastructure - as long as open, click rates etc are good - and then set a welcome flow?

Thanks for your help!

(P.s I do understand that to avoid spam filters we should send great content like a balanced image-to-text ratio etc)