It is not a bad thing at all. Will you be dinged for the inquiry? Sure but it really is miniscule and is has no weight after 12 months, and falls off of your credit report at 24 months. A 7 month loan is short term and I did the same thing but for 6 months to at least have a 'mix' of credit. You by no means need an installment loan to ever hit 850 as others on the forums have hit it without one. If anything the installment loan proves to the company you took the loan from that you can make on time payments. They may give you better loans down the road so you're building a relationship.
Once my 6 month installment is paid off, I will be taking out another installment loan myself with a 24 month term. Your credit report shows the last 24 months payments and no more so a 24 month loan make the most sense overall. A lot of stuff happens at the 24 month mark, not a new account anymore, the inquiry for the loan falls off; among a couple other things.
In the end I think you don't /need/ a loan but if you have a local bank or credit union you like, taking one out will build a relationship. If you do take one out after this one, do one for 24 months preferably if you want the best return for paying the interest.
EQ 654 -- 43 Inquiries
TU 695 -- 54 Inquiries
EX 668 -- 50 Inquiries
Utilization: 9% AAoA: 20 months Total History: 3Y
Updated: 08/04/2017 Premier 3B
