I don't think the second charge will directly impact the first charge, but it may impact how you want to handle them. To some degree what matters more is not the order that you got charged but rather the order in which you take care of them in court. This is because there are certain favorable options available to first time offenders that you could take advantage of for whichever case you handle first. But the catch is that if you get convicted in the second case that goes to court the that pretty significantly reduces the value of having avoided a conviction the first time (since you still now have a drug conviction).
My suggestion would be that you try to handle the cases together. You mentioned that you were thinking of getting a lawyer--good idea. They may be able to negotiate to have the cases handled simultaneously such that you might be able to take advantage of the first-offender programs to cover both cases. So hire a lawyer in time for your next court date, regardless of which case it is for.
No answer to these questions is intended to, nor does it, create an attorney-client relationship. There is no substitute for an actual conversation with a licensed attorney about the particular facts and circumstances of your case.
You still need to appear on the court date for the first case but your attorney may decide to continue that case to the court date of the second case. Never miss a court date. However, if you retain counsel, they may be able to go in early and continue the date. If nothing is set, be in court.