Well,.. how long have you been 4th kyu,... if you have enough time and your aikido is in a good shape there is no problem to make two test at a time,.., some times it happens in our dojos,.. but for example, in your case,.. you must do a very clear 3rd kyu and a good 2nd.
I don't know the requirements of your test, but in our case 3rd and 2nd kyu have a good number on techniques (a 2nd kyu is not a beginner). how do you feel about this? ,.. do you think you are ready to test for 2nd kyu?.
If you feel you are ready,... go ahead and do a very good test. If you don't,.. talk to your Sensei,... maybe he thinks you deserve be 2nd. kyu.
Always is good to have goals but you have to be realistic and evaluate your skill. You are the only one with the answer,…
And don't forget to enjoy your test.