Just be aware that the DL AMEX Gold does not provide an MQD waiver (this was a change that occurred on Jan 1 2020). If part of your value proposition is for an MQD waiver you would need to get the DL AMEX Plat or Reserve (though at present doesn't seem like that's something you are going after). The main DL AMEX Gold benefits are going to be free checked bag and boarding with Main Cabin 1 (which isn't a thing right now because after FC and DM they are mostly doing back to front boarding still instead of zones).

If you are just looking to maximize your ROI on travel spend there are better card than the DL AMEX Gold. Personally I think most co-branded cards are relatively worthless unless there is a specific benefit you are after (e.g., DL AMEX Plat/Reserve give you an MQD waiver).

The AMEX Gold itself provides 3x and also provides 4x on supermarkets and grocery stores which may be lucrative as a student. AMEX Membership Rewards transfer 1:1 to Delta so anything you earn on an AMEX Gold could be transferred to Delta to use toward an award ticket.

Chase Sapphire Reserve is another attractive option -- you only receive 2x for all flights but right now there is a 100k signup bonus and you can use those points at 1.25CPP for travel so that translates to $1250 you could spend straight up on tickets (or you can transfer to United and book award tickets via United).

If you do decide to stick with the Delta AMEX Gold make sure you signup with the 70k bonus offer that's out right now so you'll at least get 70k bonus miles for your minimum spend and get that in your DL SkyMiles account.