Asklemmy

At this point you are beyond doing anything about it. Now you should be focused on at least $18.

“Over the past 6 months I have met or exceeded expectations and I would like to discuss a pay increase to $18.50. I feel I have earned it and that with this salary increase I would be in a better position to contribute even more to the company.”

Ask for $18.50 and you have a better chance of getting $18.

What do you mean you "don't have any actual on paper proof"? I'm not too familiar with American law and such but don't you have a contract that states what your starting salary should be? A promise that's not put into writing and signed by your boss probably isn't worth anything.

To get a bit closer to your question: be friendly, ask if there has been a mistake or if you might have misunderstood the agreement. Only imply they're doing this on purpose if you're willing to leave the company if things go wrong.

Whenever having a tough conversation, be prepared to either accept whatever they offer or find a new job. Welcome to America, it is what it is.

You probably signed a contract initially stating the starting rate. You can ask for this. You may have been told the wrong starting salary, you may have been given the bait and switch. It is probably too late to change the past, regardless. You can ask for a raise of $0.50 starting current (or more likely next) pay period. They can say "it's not the time of year we give raises" and "your would not have been told that, it isn't our standard" etc. You can look for what their current starting rate is for the job you are currently doing and apply to the same job within the company, when asked why you are doing this you can point out you were denied market value raise.

If you already sent an email trying to talk about it, and you are trying to be natural about it, then I think that anything else might be overthinking, and possibly counter-productive.

Definitely do it in person and take the approach of “I was offered $17.50 initially and I have show I am reliable/hardworking over the last 4 months, and I would like to earn $X now” rather than “it’s not fair I was told this rate but got paid less”. Specific examples to show your value are helpful, use a friendly but firm approach, but recognize usually employers have complete discretion in wages unless you are part of union or have a contract so there’s a chance they will say no.

Another option is to use those 4 months of experience to get a new warehouse job with better pay. People tend to earn more job hopping than waiting for raises.

Better to do this in person.