Hello, yes! we've been, and kind of still are, in a similar situation.
All 3 ds's have had glue ear, ds1's picked up late once in School (although no speech delay has just been referred to SALT at 6 yrs) Its lead to no end of difficulty so its great you are picking this up before School!
Our experience was first 2 ds's had grommets within 4 months of each other - once one was picked up we saw the 'issue' if you have 3 non hearing children you don't really get its not 'normal'! ds3's 2yr check with HV was just after ds2 (3) had his grommets, HV flagged up his unclear speech and wanted to refer to SALT we held off because we felt we needed to check his hearing first. Had a hearing test 2 months later and was bad (40db - normal hearing 0-20db) and he was referred to ENT consultant (we've been very lucky to have the same consultant for all 3 boys) and put on waiting list for grommets - it was 6 weeks from seeing consultant to having grommets as day op. Why do you have to wait 3 months for your dd?
I would recommend understanding the degree of your dd's hearing loss/impairment Understanding Hearing tests - some people have also used hearing aids rather than surgery so thats always an option to explore if you do have a long wait (3 months sounds long to me, ds1 and ds3 was 6 weeks after seeing consultant, ds2 was private and done the next week).
The difference in hearing was profound for all of them once they had grommets - ds3's speech has improved immeasurably. He has been seen a couple of times last year for drop in SALT clinic so 'they can keep an eye on him' but not received therapy as he was making good progress and well supported at nursery.
I've just today asked for him to be seen again as I feel his speech has stalled and as he starts School in September I would like him to be on the waiting list for therapy now if he needs it.
If you get in the SALT system now they may well monitor as they have my ds and you get a 'direct line' back into the system (like I have today!) if she needs therapy at any point - I can't see any harm in doing both together. I know you said you are not in the UK so I'm thinking more it would be good to make contact now and get advice.
This link for NICE guidelines explain what to expect if you decide to go for grommets in the UK - where are you?
The NCDS is a great source of information and they take glue ear seriously.
Does dd go to nursery? they need to know of her difficulty and understand how to support her (this was really inportant to us as ds is in childcare 4 days a week) I give this leaflet on Guidance for teachers to EVERYONE
even my parents and in-laws have a copy 
We also did babysigning (not realising that they would all have glue ear!) but I truely believe it was a blessing, ds has unclear speech but he can communicate very well and it relieves his frustration. I believe signing supports language development - its important to understand speech and language are different.